Matt as you may or may not know I did an exact replacement aluminized cat back system for the 84-87 Turbo Regals with GM restoration stamped muffler. Also just got in stamped muffler samples for 68-72 big block Buick GS. These mufflers are made in Canada and dual wall construction like the originals. Using my connetions there, I'm waiting for stock replacement samples of the 2.25" offset/offset muffler they make in the correct dimensions for TZE.. The mufflers by PO on my 455 are the correct size except in shorter body length so there is a cheezy extra 4" lead in pipe I am not liking. I had bought the Walker Sound FX /NAPA ones listed in the interchange and though dimensionally ok they must be single wall construction due to their feather weight compared to a set of original takeoff GMC mufflers I have here. Given Bob D's story on how the single wall casing 'oil canned' and failed like a cartoon exploding cigar I wanted to get something of at least OE construction quality. I'm waiting to get these samples in and try on my coach. They won't have any number stampings on them to keep cost down, just a top quality drop in replacement for those who want to keep the stock y and 2.5" tailpipe. Not trying to start a debate on better modern systems with rear muffler etc just looking for a top quality OE replacement that won't fail and cause a burnt floor. I would say these mufflers are in a severe duty situation due to short exhaust pipes before mufflers and GVW.