Does anyone know for sure? My 5.3 is out of an Envoy, but the manifolds look to be the same as the LM7 ones (although they do have diff p/n's)...my Y-pipe doesn't even match the illustration of the 4.3 pipe when I looked to see if there was a p/n to compare. It did match the 5.3 one identically, at least visually... What chance do I have of these things mating up? I ask because it'd be a whole lot easier to cut the downpipes while the 4.3 is out...

 

as long as the 5.3 manifolds are the same as the truck ones then yes they will bolt up... might have to help them a little but they will bolt directly up to STOCK manifolds no problem...

 

my tahoe LM7 used the exact same y-pipe as the 4.3 my truck used to have. i'd imagine the envoy engine will bolt right up