Doug's Headers D303Y 1 3/4" Tri-Y Header Chevrolet Truck Big Block Chevrolet 68-87 Metallic Ceramic Coating
Part Number: D303YUPC: 694342506988
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Doug's Headers D303Y 1 3/4" Tri-Y Header Chevrolet Truck Big Block Chevrolet 68-87 Metallic Ceramic Coating
Qty: 1Disclaimer
Federal and state "anti-tampering" laws regulate modifications that affect emissions from motor vehicles and prohibit the sale, installation, and on-highway use of any add-on or modified emissions-related part on any pollution-controlled vehicle unless the part has received an exemption from the California Air Resources Board ("CARB") or is considered an exempt or replacement part. If a part has a California Executive Order Exemption (aka an EO #) or meets the requirements for an exempt part such as a Cat Back Exhaust system or is considered a replacement part, it is legal for sale or use in all 50 states. We are required by law to inform you about the legality of parts that we manufacture and sell and will refuse the sale of certain parts if the following requirements are not conformed with. Use of non compliant parts for purposes other than stated can result in a citation, fines, and/or confiscation of the vehicle. For the ordered parts listed below, you must certify, by clicking one of these boxes that you are using the product in the manner stated and for the application as specified by the manufacturer.
We cannot sell this part for use on a 1975 or Newer On Highway vehicle. It will not be added to your Cart.
Continue ShoppingEmissions Code
- Highlights
- Applications and Footnotes
- Applications and Footnotes
- Additional Information
- Download Instruction Manual
Highlights
- 3/8" Thick machined flanges...no warping
- CNC mandrel bent tubes... accurate fit & better flow
- Tri-Y headers yield maximum power from off idle to 4500 RPM making them well suited for applications demanding maximum mid-range torque with maximum fuel economy
- Heavy 16 gauge tubing...longer life
- Tubes are pre-polished to remove scratches and the header is finished with a Metallic Ceramic Thermal Barrier Coating polished to a high luster appearance offering corrosion and heat resistance up to 1400 degrees
Applications and Footnotes
Chevrolet - Class A (chevrolet chassis) |
||||||||||||
EMISSION | AUTO | STD | TUBE | COLLECTOR | PORT | |||||||
YEARS | ENGINES | CODE | A/C | P/B | P/S | COL | FLR | COL | FLR | SIZE (in.) | SIZE (in.) | SHAPE |
75 - 91 | 396-502 |
|
Y | Y | Y | Y | Y | N | N | 1 3/4 - 2 | 2 1/2 | SAP |
Available with optional smog pump provision. Dual smog pump applications add DP to the end of header part number. Single smog pump applications add SP to end of header part number | ||||||||||||
Carbureted applications only | ||||||||||||
Fits P30 chassis | ||||||||||||
Non catalytic converter equipped. | ||||||||||||
Tri-Y design | ||||||||||||
Chevrolet/GMC - GMC 2WD TRUCKS & SUV |
||||||||||||
EMISSION | AUTO | STD | TUBE | COLLECTOR | PORT | |||||||
YEARS | ENGINES | CODE | A/C | P/B | P/S | COL | FLR | COL | FLR | SIZE (in.) | SIZE (in.) | SHAPE |
68 - 87 | 396-502 |
|
Y | Y | Y | Y | Y | Y | Y | 1 3/4 - 2 | 2 1/2 | SAP |
Available with optional smog pump provision. Dual smog pump applications add DP to the end of header part number. Single smog pump applications add SP to end of header part number | ||||||||||||
Big block frame stands and motor mounts must be used to insure proper engine location and header fit. | ||||||||||||
Does not fit 4 speed applications with bell housing mounts | ||||||||||||
Non catalytic converter equipped. | ||||||||||||
Tri-Y design | ||||||||||||
Chevrolet/GMC - 1/2, 3/4, 1 Ton / 1500, 2500, 3500 TRUCKS |
||||||||||||
EMISSION | AUTO | STD | TUBE | COLLECTOR | PORT | |||||||
YEARS | ENGINES | CODE | A/C | P/B | P/S | COL | FLR | COL | FLR | SIZE (in.) | SIZE (in.) | SHAPE |
68 - 87 | 396-502 |
|
Y | Y | Y | Y | Y | Y | Y | 1 3/4 - 2 | 2 1/2 | SAP |
Available with optional smog pump provision. Dual smog pump applications add DP to the end of header part number. Single smog pump applications add SP to end of header part number | ||||||||||||
Big block frame stands and motor mounts must be used to insure proper engine location and header fit. | ||||||||||||
Does not fit 4 speed applications with bell housing mounts | ||||||||||||
Non catalytic converter equipped. | ||||||||||||
Tri-Y design | ||||||||||||
Chevrolet/GMC - 1 Ton / 3500 Crew, Standard Cab DUALLY |
||||||||||||
EMISSION | AUTO | STD | TUBE | COLLECTOR | PORT | |||||||
YEARS | ENGINES | CODE | A/C | P/B | P/S | COL | FLR | COL | FLR | SIZE (in.) | SIZE (in.) | SHAPE |
73 - 91 | 396-502 |
|
Y | Y | Y | Y | Y | Y | Y | 1 3/4 - 2 | 2 1/2 | SAP |
Available with optional smog pump provision. Dual smog pump applications add DP to the end of header part number. Single smog pump applications add SP to end of header part number | ||||||||||||
Big block frame stands and motor mounts must be used to insure proper engine location and header fit. | ||||||||||||
Does not fit 4 speed applications with bell housing mounts | ||||||||||||
Non catalytic converter equipped. | ||||||||||||
Tri-Y design | ||||||||||||
Chevrolet/GMC - 1 Ton / 3500 Crew, Standard Cab DUALLY |
||||||||||||
EMISSION | AUTO | STD | TUBE | COLLECTOR | PORT | |||||||
YEARS | ENGINES | CODE | A/C | P/B | P/S | COL | FLR | COL | FLR | SIZE (in.) | SIZE (in.) | SHAPE |
73 - 91 | 396-502 |
|
Y | Y | Y | Y | Y | Y | Y | 1 3/4 - 2 | 2 1/2 | SAP |
Available with optional smog pump provision. Dual smog pump applications add DP to the end of header part number. Single smog pump applications add SP to end of header part number | ||||||||||||
Big block frame stands and motor mounts must be used to insure proper engine location and header fit. | ||||||||||||
Does not fit 4 speed applications with bell housing mounts | ||||||||||||
Non catalytic converter equipped. | ||||||||||||
Tri-Y design | ||||||||||||
Chevrolet/GMC - Blazer / Jimmy, Suburban, Tahoe / Yukon |
||||||||||||
EMISSION | AUTO | STD | TUBE | COLLECTOR | PORT | |||||||
YEARS | ENGINES | CODE | A/C | P/B | P/S | COL | FLR | COL | FLR | SIZE (in.) | SIZE (in.) | SHAPE |
68 - 87 | 396-502 |
|
Y | Y | Y | Y | Y | Y | Y | 1 3/4 - 2 | 2 1/2 | SAP |
Available with optional smog pump provision. Dual smog pump applications add DP to the end of header part number. Single smog pump applications add SP to end of header part number | ||||||||||||
Does not fit 4 speed applications with bell housing mounts | ||||||||||||
Non catalytic converter equipped. | ||||||||||||
Tri-Y design |
Applications and Footnotes
Chevrolet - Class A (chevrolet chassis) |
||||||||||||
YEARS | 75 - 91 | |||||||||||
ENGINES | 396-502 | |||||||||||
EMISSION CODE |
|
|||||||||||
A/C | Y | |||||||||||
P/B | Y | |||||||||||
P/S | Y | |||||||||||
AUTO COL | Y | |||||||||||
AUTO FLR | Y | |||||||||||
STD COL | N | |||||||||||
STD FLR | N | |||||||||||
TUBE SIZE (in.) | 1 3/4 - 2 | |||||||||||
COLLECTOR SIZE (in.) | 2 1/2 | |||||||||||
PORT SHAPE | SAP | |||||||||||
Available with optional smog pump provision. Dual smog pump applications add DP to the end of header part number. Single smog pump applications add SP to end of header part number | ||||||||||||
Carbureted applications only | ||||||||||||
Fits P30 chassis | ||||||||||||
Non catalytic converter equipped. | ||||||||||||
Tri-Y design | ||||||||||||
Chevrolet/GMC - GMC 2WD TRUCKS & SUV |
||||||||||||
YEARS | 68 - 87 | |||||||||||
ENGINES | 396-502 | |||||||||||
EMISSION CODE |
|
|||||||||||
A/C | Y | |||||||||||
P/B | Y | |||||||||||
P/S | Y | |||||||||||
AUTO COL | Y | |||||||||||
AUTO FLR | Y | |||||||||||
STD COL | Y | |||||||||||
STD FLR | Y | |||||||||||
TUBE SIZE (in.) | 1 3/4 - 2 | |||||||||||
COLLECTOR SIZE (in.) | 2 1/2 | |||||||||||
PORT SHAPE | SAP | |||||||||||
Available with optional smog pump provision. Dual smog pump applications add DP to the end of header part number. Single smog pump applications add SP to end of header part number | ||||||||||||
Big block frame stands and motor mounts must be used to insure proper engine location and header fit. | ||||||||||||
Does not fit 4 speed applications with bell housing mounts | ||||||||||||
Non catalytic converter equipped. | ||||||||||||
Tri-Y design | ||||||||||||
Chevrolet/GMC - 1/2, 3/4, 1 Ton / 1500, 2500, 3500 TRUCKS |
||||||||||||
YEARS | 68 - 87 | |||||||||||
ENGINES | 396-502 | |||||||||||
EMISSION CODE |
|
|||||||||||
A/C | Y | |||||||||||
P/B | Y | |||||||||||
P/S | Y | |||||||||||
AUTO COL | Y | |||||||||||
AUTO FLR | Y | |||||||||||
STD COL | Y | |||||||||||
STD FLR | Y | |||||||||||
TUBE SIZE (in.) | 1 3/4 - 2 | |||||||||||
COLLECTOR SIZE (in.) | 2 1/2 | |||||||||||
PORT SHAPE | SAP | |||||||||||
Available with optional smog pump provision. Dual smog pump applications add DP to the end of header part number. Single smog pump applications add SP to end of header part number | ||||||||||||
Big block frame stands and motor mounts must be used to insure proper engine location and header fit. | ||||||||||||
Does not fit 4 speed applications with bell housing mounts | ||||||||||||
Non catalytic converter equipped. | ||||||||||||
Tri-Y design | ||||||||||||
Chevrolet/GMC - 1 Ton / 3500 Crew, Standard Cab DUALLY |
||||||||||||
YEARS | 73 - 91 | |||||||||||
ENGINES | 396-502 | |||||||||||
EMISSION CODE |
|
|||||||||||
A/C | Y | |||||||||||
P/B | Y | |||||||||||
P/S | Y | |||||||||||
AUTO COL | Y | |||||||||||
AUTO FLR | Y | |||||||||||
STD COL | Y | |||||||||||
STD FLR | Y | |||||||||||
TUBE SIZE (in.) | 1 3/4 - 2 | |||||||||||
COLLECTOR SIZE (in.) | 2 1/2 | |||||||||||
PORT SHAPE | SAP | |||||||||||
Available with optional smog pump provision. Dual smog pump applications add DP to the end of header part number. Single smog pump applications add SP to end of header part number | ||||||||||||
Big block frame stands and motor mounts must be used to insure proper engine location and header fit. | ||||||||||||
Does not fit 4 speed applications with bell housing mounts | ||||||||||||
Non catalytic converter equipped. | ||||||||||||
Tri-Y design | ||||||||||||
Chevrolet/GMC - 1 Ton / 3500 Crew, Standard Cab DUALLY |
||||||||||||
YEARS | 73 - 91 | |||||||||||
ENGINES | 396-502 | |||||||||||
EMISSION CODE |
|
|||||||||||
A/C | Y | |||||||||||
P/B | Y | |||||||||||
P/S | Y | |||||||||||
AUTO COL | Y | |||||||||||
AUTO FLR | Y | |||||||||||
STD COL | Y | |||||||||||
STD FLR | Y | |||||||||||
TUBE SIZE (in.) | 1 3/4 - 2 | |||||||||||
COLLECTOR SIZE (in.) | 2 1/2 | |||||||||||
PORT SHAPE | SAP | |||||||||||
Available with optional smog pump provision. Dual smog pump applications add DP to the end of header part number. Single smog pump applications add SP to end of header part number | ||||||||||||
Big block frame stands and motor mounts must be used to insure proper engine location and header fit. | ||||||||||||
Does not fit 4 speed applications with bell housing mounts | ||||||||||||
Non catalytic converter equipped. | ||||||||||||
Tri-Y design | ||||||||||||
Chevrolet/GMC - Blazer / Jimmy, Suburban, Tahoe / Yukon |
||||||||||||
YEARS | 68 - 87 | |||||||||||
ENGINES | 396-502 | |||||||||||
EMISSION CODE |
|
|||||||||||
A/C | Y | |||||||||||
P/B | Y | |||||||||||
P/S | Y | |||||||||||
AUTO COL | Y | |||||||||||
AUTO FLR | Y | |||||||||||
STD COL | Y | |||||||||||
STD FLR | Y | |||||||||||
TUBE SIZE (in.) | 1 3/4 - 2 | |||||||||||
COLLECTOR SIZE (in.) | 2 1/2 | |||||||||||
PORT SHAPE | SAP | |||||||||||
Available with optional smog pump provision. Dual smog pump applications add DP to the end of header part number. Single smog pump applications add SP to end of header part number | ||||||||||||
Does not fit 4 speed applications with bell housing mounts | ||||||||||||
Non catalytic converter equipped. | ||||||||||||
Tri-Y design |
Additional Information
Doug's 2/4 WD TRUCK HEADERS Tri-Y Metallic Ceramic Coated Header development and design is complex and requires a substantial amount of time and resources to do the job right! Many manufacturers are unwilling to make the commitment and instead offer compromised headers at lower prices. Doug's will not compromise performance, quality or fit to compete with inferior designs at cheap prices. Every Doug's header is tuned with the proper tube size and length to efficiently remove all the exhaust from each cylinder, reducing pumping losses resulting in a dramatic increases in horsepower and torque. Doug's headers are carefully developed on the vehicles they are intended to fit and are re-checked numerous times during the design and manufacturing process.
Download Instruction Manual
Emissions Code
PerTronix Performance Ignition and Exhaust Brands use a voluntary product identification program whereby all emission sensitive products can be identified by placing numbered labels in product packaging and listing corresponding numeric codes next to each part number. The corresponding numbers and explanations are as follows:This Product has been granted a California Air Resources Board (C.A.R.B.) Executive Order ("EO") Exemption, or is considered a Direct Replacement or Consolidated Replacement part. It is 50 State Legal when installed on the appropriate vehicle per the Manufacturer Application guide and Installation Instructions.
This product is Legal for use on 1974 and older non catalyst equipped vehicles and is considered a Replacement Part per California Air Resources Board regulations, as long as ALL emissions sensitive components are retained, including A.I.R., EGR, Heat Risers etc. Failure to retain any of these components, or use on any 1975 or newer catalytic converter equipped car would render this product Illegal for Street or Off Highway use in California, or in states that have adopted California Emissions regulations and may only be used for Closed Course Competition.
This product is Not legal for Street or Off Highway use in California or in states that have adopted California Emissions Regulations and is only intended for Closed Course Competition use, except 1965 and older US manufactured California Certified vehicles, 1967 or older US manufactured Federally Certified vehicles, or 1967 and older Foreign manufactured vehicles which may have any aftermarket add-on or modified part installed as long as the vehicle can still meet the tailpipe emissions standards for the year of the vehicle and retain any original or retrofit crankcase control (PCV) devices and NOx device required for the year of the vehicle.