'77 & '78 front & rear Y exhaust pipes

[Steven B.]

My parts books are in storage. Are the '77 L-82 and the '78 L-48 front and rear exhaust Y pipes (exhaust manifolds to cat and cat to mufflers) the same? Thanks, Steve

[Tom R.]

Re: '77 & '78 front & rear Y exhaust pipes

My parts books are in storage. Are the '77 L-82 and the '78 L-48 front and rear exhaust Y pipes (exhaust manifolds to cat and cat to mufflers) the same? Thanks, Steve

Steven

Good question. My quess is that the fronts are the same but the rears are a different size. The 1978...mufflers and rear pipes were tucked up under to be less visible from the rear from 1968-77 vettes. Thus the pipes for the L48 are (in 78) smaller and have that flattened look. 1978 Mufflers were smaller as well to allow more "tuck." In general, you're good through the cat converter but after that it changes due to the changes to accommodate the expanded fuel tank, rear storage capacity and something else I have yet to think of...hope this helps.

[Paul D.]

Re: '77 & '78 front & rear Y exhaust pipes

According to my GM parts catalog dated 3/83, the front pipe #s are 371789 federal and 356947 California regardless of engine 77-79. The rear, however, shows 357780 for 77 and 459080 for 78-79 also regardless of engine. Hopefully, Joe L will chime in with any supercession info. Chip.

[Joe L.]

Re: '77 & '78 front & rear Y exhaust pipes

My parts books are in storage. Are the '77 L-82 and the '78 L-48 front and rear exhaust Y pipes (exhaust manifolds to cat and cat to mufflers) the same? Thanks, Steve

Steve------


The 1977 and 1978 front "Y" pipes were the same regardless of engine. Both years used GM #371789. California emissions may have used GM #356947 but I cannot confirm that.

The 1977 rear exhaust "Y" pipe was GM #357780 for both engines. The 1978 rear exhaust "Y" pipe was the same as 1977 for L-48. However, for 1978 L-82 the rear pipe was GM #459080.

You don't need to worry about ordering any of these from your GM dealer. All are discontinued without supercession. Dates of discontinuation are as follows:

371789-------November, 1992

356947-------October, 1986

357780-------January, 1983

459080-------November, 1992

[Steven B.]

Re: '77 & '78 front & rear Y exhaust pipes

Thanks Guys! I have the '77 front and rear pipes I removed from my '77 L-82 in December 1976. The rear on the '78 SA L-48 my Dad and I ordered and took delivery late '77 has a rusted rear and I was thinking of swapping but on second thought I think I will leave it original as I am not driving it on the road. Thanks again! Steve