Can You Help Me ID These Mufflers?

[musclecar fan]

I'm stumped on 2 transverse mufflers I have.

One is marked "GM 3996331 W" on the muffler.

The other muffler I have is marked &quot;83<span style="font-size: 11pt">3979</span>69&quot; with the &quot;83&quot; and the &quot;69&quot; a little smaller in letter size. This muffler also says &quot;INLET&quot; and &quot;8 H 8&quot; which I'm guessing is a date code.

Any help in ID'ing this is very much appreciated. I accumulated this from an estate of someone who specialized in 67-70 Camaro's.

If you provide me with an e-mail address I can also send pictures to you.

Thanks

[musclecar fan]

Can anyone with an old parts book tell me what these are for please. Thanks

[al8apex]

Are both 2 in and 2 out?

My 1971 Chevy (71 only) parts book shows the 3996331 as a Camaro muffler, 350 w/4bc AND 400 w/4bc, that means SS 350 &amp; 396 &amp; Z28 IMHO

My all Chevy through 75 shows the above for 71-74 w/4bc, NOT 70 though, that number is 3983066 ...

not for Novas either

Hope that helps

no sign of the other number ...

the 8 in front of the other part number is odd, not a normal Chevy number, it MAY be a Firebird or a 74 GTO (Nova), I do not have any Pontiac books that go back that far

[musclecar fan]

Thanks Jim,

Yes they are both 2 in 2 out. Can I e-mail you a picture of the number layout on the second muffler? What e-mail should I send it to?

Thanks, Mark