[William]

When NC8 was dropped as standard equipment, the 1st recall notice stated Camaro SS L34 & L78 would be produced with the standard N10 muffler/resonator dual exhaust system. The parts in question are the BB exhaust pipes [grp. 3.609] from the manifolds back. The 67-68 deep-tone pipes [no resonators] are 3912596 and 3923573. They are also listed as the exhaust pipes for the 69 L35 396 in an 11/68 P & A manual. The '69 L34 & L78 396 lists different part numbers, 3958409 & 3958410. There is a note stating they run from the manifolds to the 'front' muffler. In production, the resonators were welded to the exhaust pipes. When serviced, the parts were separate.

However, the AIM lists different numbers: 3923567 & 3912592. The rev box as of June 13, 1969 shows "3923567 was 3923573; 3912592 was 3912596." This contradicts the 11/68 P & A manual which implies L35 396s did not have resonators. PNs #3923567 & 3912592 are also listed in the '67 AIM under N10 as L78. Probably resonator pipes.

The April recall notice has a parts list to convert a BB built with NC8 to "...a regular muffler system." The exhaust pipes listed are 3912596 and 3923573. That means any recalled BB was fitted with a single muffler no resonator system.

So, what did they do in production? ZL-1 #3 and the recent L78 survivor, both built early ’69, had the muffler/resonator system. I know of two later production L35s built w/o resonators. My guess, the clue in the 11/68 P & A is telling: L35 cars were built w/o resonators, L34, L78 & COPOs had the full muffler/resonator system. We did a ZL-1 resto many years ago, full N10 system. Had a nice sound, not at all loud. Another ZL-1 resto was done w/o resonators and was obnoxiously loud. L72 & L78 cars w/o resonators have an unpleasant, raspy tone.

Wish I had more Chassis Broadcast Copies. Box 198 lists an exhaust system code.

L35 built 10/9/68...FR probably no resonators
L78 built 11/10/68...FT probably chambered
ZL-1 built 12/30/68, L78 built 1/2/69, L34 built 1/13/69, COPO built 5/7/69, L78 built 6/23/69...FS probably muffler/resonator.