Thornton's Small Block JR Exhaust Manifolds

Here is a high performance exhaust manifolds that GM never produced. We have designed and produced what everybody was asking for; true dual exhaust cast iron manifold. This is the performance solution instead of headers. Features: Large 2 1/4" outlet on the driver and passenger side manifolds (original stock manifolds are 2"). The crossover pipe is eliminated from the passenger side. The inner port design is larger with center divider for better air flow. Direct bolt on with no modifications. They will fit 1964 to 1988 small block Oldsmobile egines (307, 330, 350, 403). Will fit all GM A body cars, G body cars, F body Trans Am with a 403, and 1971 and newer B and C body cars. 

Thornton's Small Block JR Exhaust Manifolds

  • Satisfaction guaranteed. All returns and exchanges are accepted within 30 days; no questions asked. The part must meet the following requirements:​

    • Part is unused

    • Part is unaltered

    • Part is in original finish

    • Part to be shipped back with original packaging 

    ​We must be notified about the return so we can ensure a proper return/exchange process. We will send a call tag or return label via email. Shipping charges cannot be refunded, and customer pays return shipping.

    Returns are subject to restocking fees if not returned in original packaging or deemed poorly repackaged. Any and all fees and duties associated with your purchase, are your responsibily.