I am in the middle of a project, my 90 3500 dually originally had a 454 and 700r someone took it out and put a 350 in it, he passed away and his kids didn't want to finish it so I got it cheap, finished bolting it up and it wouldn't move ends up they swapped tranny also 4l80e out of a 93. I swapped tranny for a good old th400, every thing ran great for about 4 yrs then 350 got sick, I bought a 6.2 out of an 87 ton truck, but when I got it home I ran the numbers and it's an 84 c code. all egr crap was unhooked so I removed it all. now i'm trying to find a y pipe for it but no one lists it, muffler shop can make it no problem but I'll have to haul the truck to town. the manifold outlets are 2" with 2-3/4 flange holes where the later ones are 2-1/4" with 3" flange hole spacing. this truck has the 3" banks exhaust on it already and would like to keep it.