1979 Cutlass & Hurst Exhaust

Rocket350

Not-quite-so-new-guy
Oct 27, 2021
44
18
Charlevoix, MI
Not sure if this will help with trying to find the lenth needed for the cat but p/n for '79 was 8998692. It was used with the L34 (Olds 350), LM1 (SBC 350) & LG4 (SBC 305). Another thing for future reference is the L34 & LM1 used the same complete exhaust from the cat back as with the LG4 with GU2/M20. The LG4 with GH2/GU1 & M29/M33/MV9 used only a different muffler/tailpipe.
I was able to find a NOS CAT for the '79 Supreme with the 8998598 cat. It was for the equipped 260 V8. I believe the dimensions are the same other than the inlet and outlet pipes are a bit smaller. The gentleman that had that cat was gracious enough to get me the dimensions from that. The 8998692 has the following detents as well 8998782 and 8898876. I would like to confirm the inlet and outlet size of the 8998692 as I am still not 100% sure on that but I can take the measurement of the down pipe that my builder has and measure the exhaust pipe that I have and it should work. It was the length that was the main measurement. The 8998598 length is 22 inches overall. Okay, now that I confused myself, the next tough part is going to be finding a flange that will accept the cat bracket that mounts on the trans bracket. Thanks for the additional info everything helps at this point!
 

Rocket350

Not-quite-so-new-guy
Oct 27, 2021
44
18
Charlevoix, MI
I was able to find a NOS CAT for the '79 Supreme with the 8998598 cat. It was for the equipped 260 V8. I believe the dimensions are the same other than the inlet and outlet pipes are a bit smaller. The gentleman that had that cat was gracious enough to get me the dimensions from that. The 8998692 has the following detents as well 8998782 and 8898876. I would like to confirm the inlet and outlet size of the 8998692 as I am still not 100% sure on that but I can take the measurement of the down pipe that my builder has and measure the exhaust pipe that I have and it should work. It was the length that was the main measurement. The 8998598 length is 22 inches overall. Okay, now that I confused myself, the next tough part is going to be finding a flange that will accept the cat bracket that mounts on the trans bracket. Thanks for the additional info everything helps at this point!
IMG_20220715_204241.jpg
 

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