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Doug Thorley Headers THY-300Y-C GM Truck 1961-87

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Doug Thorley Headers THY-300Y-C GM Truck 1961-87

Create More Horsepower And Torque !!

Doug Thorley Headers THY-300Y-C
1961-1966 Chevy and GMC Truck and Suburban
Automatic Transmission ONLY
Coil Spring Front Suspension ONLY
1973-1987 Chevy Truck, Suburban, Blazer and GMC Jimmy
Manual and Automatic Transmission
2WD/4WD,   SBC,   Tri-Y   Dual Exit
Ceramic Coated Silver

Made in the USA.

 50 State Smog Legal

CARB E.O. # D-540-5 

Availability: In stock

Regular Price: $878.00

Special Price $595.00

Doug Thorley Headers THY-300Y-C are designed to outflow your stock exhaust manifolds. These headers increase gas mileage and give your engine more horsepower across the entire RPM range. The Tri-Y configuration builds the most power in the middle RPM range, which is great for towing and steep grades. To make these headers last, Doug Thorley Headers made them out of durable 14-gauge mild steel with 3/8 in. thick flanges and 5/16 in. collector rings. To prevent leaks, these headers have an O-ring welded into the flange, in addition to the high-temperature gasket provided.

Unless otherwise noted, these headers are designed to fit the vehicle as it came from the manufacturer. This includes components like cylinder heads, chassis, steering, motor mounts, body mounts and bushings, etc.

If your vehicle is using aftermarket components, parts from other applications, or custom altered parts, then it is the installer's responsibility to verify fitment.


Brand: Doug Thorley Headers

Manufacturer's Part Number: THY-300Y-C

Part Type: Headers

Product Line: Exhaust

Header Style:     Tri-Y

Header Material:     Steel

Header Finish:     Silver ceramic coated

Primary Tube Diameter (in):     1 5/8 in.

Collector Attachment:     3-bolt flange

Collector Diameter:     2.500 in.

Tuned:     No

Primary Tube Gauge:     14-gauge

Flange Style:     Standard

Flange Thickness (in):     3/8 in.

Bolts/Studs Included:     Yes

Gaskets Included:     Yes

Reducers Included:     No

Y-Pipe Included:     No

Motor Mounts Included:     No

Transmission Mount Included:     No

Quantity:     SOLD AS A PAIR

Drivetrain     4WD

Power Steering     Yes

Power Brakes     Yes

Air Conditioning     Yes

Standard Transmission Column Shift     No

Standard Transmission Floor Shift     No

Automatic Transmission Column Shift     Yes

Automatic Transmission Floor Shift     Yes

Application Footnotes:     

Will fit with angle plug heads.

May require alternator/generator bracket.

Will require air conditioning bracket on models equipped with "long" style compressor (1988 and earlier).

Specify A/C compressor mounting location. L/S bracket P/N 8506. R/S Bracket P/N 8506.



Doug Thorley Headers carry a lifetime warranty against defects in material and workmanship to the original purchaser. Chrome plated items carry no warranty for finish, other than to be free from defects at the time of purchase, prior to installation. This warranty does not cover damage caused by misuse, abuse, collisions, improper installation, alterations, off-road use, racing use, commercial use, "burn-out" or cracking caused by excessive heat, superchargers, or external heat insulating wrap. Rust or corrosion that occurs after the product is installed is also not covered.

year make model 1961-1987 GM Truck, Suburban, Blazer, Jimmy

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