61/62 Off Road Mufflers

[Peter M.]

For 1961/1962 Corvette ... I have a pair of what I I believe to be an original pair of off road mufflers with GM part numbers as well as a pair of reproduction units. The original GM are internal two pipe design (bottom picture) while the repro is a chambered "straight through" design. Does the original correspond to what you know as original units? If so ... do other repro suppliers offer the same as original internal design or just the chambered straight through design? I would imagine that the repro would be louder.

[Steven B.]

Re: 61/62 Off Road Mufflers

Peter, I have to get mine out of storage to look and compare to yours. I got them in the late 60's at my local Chevy dealer and they are still in the box. I do recall a couple of years ago comparing off road units from two retailers and they were the same.

[Peter M.]

Re: 61/62 Off Road Mufflers

Steven
Looking forward to your finding when you locate those original Off Road mufflers!
Thanks
Peter

[David B.]

Re: 61/62 Off Road Mufflers

Peter,
What is the part number for your original GM off road muffler. I believe I have the lay out prints with GM photos of the installation of that option.

[Peter M.]

Re: 61/62 Off Road Mufflers

Hi David,
The part numbers are as follows:

GM 3798789
GM 3798790

Thanks for looking into this.

Peter

[Peter M.]

Re: 61/62 Off Road Mufflers

Sorry - those GM numbers I just provided were the header pipes - mufflers only have embossed (raised) on muffler body 21132 0 A on both - no GM tag ... likely are service replacement I suspect

[Dennis C.]

Re: 61/62 Off Road Mufflers

Sorry - those GM numbers I just provided were the header pipes - mufflers only have embossed (raised) on muffler body 21132 0 A on both - no GM tag ... likely are service replacement I suspect

Can you post a photo of the outside of the off road mufflers you thought might be original?

[David B.]

Re: 61/62 Off Road Mufflers

Sorry - those GM numbers I just provided were the header pipes - mufflers only have embossed (raised) on muffler body 21132 0 A on both - no GM tag ... likely are service replacement I suspect

I kinda thought so since they are listed in Grp. 3.609 not the muffler Grp.3.701. The layout print I have predates your part numbers. I think Engineering for this option was originally intended for '60 LeMans with updates in late '61 tied to Front auxiliary stabilizer unit 3823052. A couple of notations indicate 2.25 dia. seamless tubing utilized and for "Racing use" a 2.25 dia. hole was bored thru the length of the muffler. The muffler listed was made from #3741413. This is listed in 1960 from Grp. 3.701 as a truck muffler with a length of 38 5/8 OL. Sorry I could not help more.

[Peter M.]

Re: 61/62 Off Road Mufflers

Thanks David - much appreciated - I've attached additional pictures as Dennis Crupi requested.

[Peter M.]

Re: 61/62 Off Road Mufflers

As requested - see pictures

[Dennis C.]

Re: 61/62 Off Road Mufflers

As requested - see pictures

I was looking for those spot welds around the circumference. Thanks for posting.

[Peter M.]

Re: 61/62 Off Road Mufflers

So Dennis - reference those spot welds ... is your conclusion then that these examples are indeed original OEM Off Road mufflers which would have been installed on 1961/1962 Corvettes? Further that the two-tube inner tube design was factory vs the reproduction single tube reproduction?

[Peter M.]

Re: 61/62 Off Road Mufflers New News!

David - I realized that the mufflers do in fact have GM part numbers stamped on the pipes close to the weld to the muffler itself. One is 3813535 - the other opposite muffler has 38135XX with last two covered by the factory weld!

[Dennis C.]

Re: 61/62 Off Road Mufflers

So Dennis - reference those spot welds ... is your conclusion then that these examples are indeed original OEM Off Road mufflers which would have been installed on 1961/1962 Corvettes? Further that the two-tube inner tube design was factory vs the reproduction single tube reproduction?

I can not comment on the inner tube design.

I have attached two photos of off road mufflers from a 1957 4 star Bowtie car. If it wasn't for the part number (211320A) on your mufflers, I would say they look extremely similar.

[Dennis C.]

Re: 61/62 Off Road Mufflers New News!

David - I realized that the mufflers do in fact have GM part numbers stamped on the pipes close to the weld to the muffler itself. One is 3813535 - the other opposite muffler has 38135XX with last two covered by the factory weld!

The number 3813535 do not appear in the February 1961 Chevrolet Parts Manual.

However, you might want to take a look at this post on the other forum:
https://www.corvetteforum.com/forums...-mufflers.html