So I am finishing up a 5.3 swap into an 85 K5 and I am down to exhaust as a final hurdle. This is a CA truck and must pass the Referee inspection. The motor is a crate replacment and I its being built out as an 04 as I already had all the components from an old 5.3 that was a custom job from the intake to accessories to exhaust so it was easy to save a bunch of cash by reusing all those parts.

I have done a swap into a 96 Sierra 2wd and was able to use the factory cats and crossover and while a bit tight in a few spots, it worked out just fine. What I am unsure about is if I can do this on the K5? I can get the exhaust from a yard for $275 or I can buy a set of aftermarket CARB legal cats for the engine for 300 but then I need to build out the entire exhaust from the flanges bak instead of fabbing up a catback if I use the factory stuff. This would save quite a bit of time and money if it works.

Im also wanting to use the factory setup as the Referees are ***** and I've seen swaps get hassled for cats being too far away even though they wouldnt physically fit at the distance they came on the original vehicle. The more stock equipment the better.

Does anyone have experience with this particular setup that can verify a bolt on fit with some frame clearancing at the very worst but otherwise works just fine? Im pushing to get this up and running within the week and if I can save myself 400 dollars in materials and time to scratch build something, I am miles ahead and can worry about all the other little issues that come up.