Early 69 under car exhaust

[Anthony C.]

I just stumbled on 2 NOS 2" mufflers brand new in the boxes unopened until yesterday. It has the old style spotted galvanized look and that deep groove at the crimp. I have pics on my phone but my i phone is not cooperating with me. On one muffler it says Inlet 5 H 3 73397034i only opened one box. On the individual boxes they have a GM part # 3960602 Right and 3960601 Left. The guy that has them says he bought them in the mid 70's and never used them. Would these be correct for a Nov 68 car.

[Grant W.]

Re: Early 69 under car exhaust

Hi Anthony
The mufflers you have fit SB 69 350, BB 69 427 also fits 71 350hp. This is a 2 inch muffler system.

Thanks, Grant

[Anthony C.]

Re: Early 69 under car exhaust

Grant
Would i have to do some fancy welding to make these into a two pipe system to make them appear as typical factory production or can i go the 3 piece route with out any major deductions. And i know the date codes are going to be wrong. Is that what the 5 H 3 means date of manufacture?

[Joe L.]

Re: Early 69 under car exhaust

Grant
Would i have to do some fancy welding to make these into a two pipe system to make them appear as typical factory production or can i go the 3 piece route with out any major deductions. And i know the date codes are going to be wrong. Is that what the 5 H 3 means date of manufacture?

Anthony------


The part numbers are correct for any 1969-72 2" system. However, these are SERVICE-only mufflers and have the extension with slip joint which is unique to SERVICE muffler assemblies. The mufflers, themselves, are the same as PRODUCTION (except for embossings).

In order to re-create the original exhaust pipe/muffler configuration you will, indeed, need to do some "fancy welding".

One curious thing: during the many years of my life with my 1969, I purchased quite a few GM #3960602 mufflers. Every one I ever purchased had the lower muffler black-out pre-applied out-of-the-box.

[Anthony C.]

Re: Early 69 under car exhaust

Joe
Interesting the muffler that i took out of the box has no blackout applied. Just has the spotted galvanizing. I knew they were over the counter service mufflers. I was right on that point. I was just wondering since they have the part # embossed on them on. The part # on the muffler is not 3960602 it is 73397034 what does this number correspond to? 3960602 hand written on the box.

[Joe L.]

Re: Early 69 under car exhaust

Joe
Interesting the muffler that i took out of the box has no blackout applied. Just has the spotted galvanizing. I knew they were over the counter service mufflers. I was right on that point. I was just wondering since they have the part # embossed on them on. The part # on the muffler is not 3960602 it is 73397034 what does this number correspond to? 3960602 hand written on the box.

Anthony------


I never had one that had the 3960602 or 3960603 part number embossed on the muffler. As I recall, there were other numbers, maybe like the one you describe. Just what that number means I have no idea. It's not a GM part number, though.

Given that the GM part numbers are hand-written on the boxes, are you sure that what's inside actually are GM parts? It could be that someone just wrote the "equivalent" GM part numbers on the boxes. In that regard, the GM mufflers I recall did not have obvious galvanized finish wraps on the non-painted area. It may well have been galvanized, but it was absolutely NOT the "splotchy" appearance of traditional galvanizing.

[Grant W.]

Re: Early 69 under car exhaust

Hi Joe
Just looked at my NOS 3960602 Right and 3960601 Left.
Both have the embossed numbers 3960601 and 3960602 on the mufflers.

GM
3960601
WI 81

Incidentally the 601 muffler is not blacked out where as the 602 is completely blacked out. Even the pipes are painted.
Hope this helps.
Grant