What’s with the indentation on the GM mufflers?

[Barn Owl]

I have had this question ever since I opened the tailgate on my bus: Why do the GM's have an indentation on the backside of their mufflers? It doesn't seem to be there for any clearance issues. I don't know how many models used them, but I have seen them on the 4106s and 4107s.

Just want to know.

Laryn

[Ncbob]

You can't imagine how I honestly tried to balance the ying and yang of this question before bringing myself to ask one myself........

Could it be the result of the push starts from MCI's?

Egads! Am I ever going to get flamed for that one!

Bob

[FloridaCliff]

Bob,

You better be sleeping with one eye open!!!!!!!!   

I thought you would be over that GM jealousy by now...LOL   

Remember as I said the other day " the only thing that could be improved on your MCI-5 was if it had a GMC emblem"          

Cliff

[Dallas]

Bob,

Keep Your GM ALL GM!

[kyle4501]

Ole Bob is just jealous of GM's.

I'll bet he really wants a scenicruiser 

[Utahclaimjumper]

I went out and checked my 06 muffler. no indentations, perfect cylinder top to bottom.>>>Dan

[superpickle]

 ........... .............. Please continue the petty bickering ......

[kyle4501]

Hey Bob, if mci's are so great, how did all the GMC's get in front?

   

[RJ]

Hey Bob, if mci's are so great, how did all the GMC's get in front?

Easy, Kyle - alphabetical   

[kyle4501]

Easy, Kyle - alphabetical  

Waht if yuor'e dyslexic?

BTW Bob's in NC, are you sure he can spell? 

[uncle ned]

    Looked at the muffler on my 04, no indention but kept looking up it and found a couple old mci's. cleaned them out and cured my heating problems. been hunting that problem for years.

uncle ned
"Huggy Bear"

[Dallas]

My 2¢.....

I think the indentation is from some mechanic sitting down there banging his head and trying to figure out what the previous guy did to get it into this condition.

[Hi yo silver]

Ya See, Laryn...
I told ya there were lots of helpful and intelligent guys on this board! ...I'm sitting here grinning and shaking my head...he! he!

[Buffalo SpaceShip]

Laryn... OK, seriously. My old '06 did not have "the dent" and my current '08's is so far up and back behind the engine I'd never know if it did, but I have seen my fair share of "dented" ones in pics that it must have been an option or factory alteration at some point. Maybe to provide clearance for lid actuators or something.

There's a few GMC buses on eBay right now that indeed have "the dent".

FWIW,
Brian B.

[Barn Owl]

I think the ones without the dent are not OEM mufflers. My manual shows the dent. I have seen a few without, but thats not the norm for what I have seen. Your right, I've been thinking too hard!