Hello,
I have an 85 camaro and I also have a truck with an 8.1l and a t56 transmission. I want to swap the 8.1 into the camaro. My question is can I use the trucks wiring harness in the camaro?

 

Oh boy, I would be more worried about the trans fitting. The T56 was not installed behind an 8.1l. There was a HD ZF 6speed that is enormous and would never fit in the trans tunnel.

 

Looking the one at my work, the bellhousing pattern looks like traditional chevy v8. I don't know if the transmission would be an issue. I would think it being a tall deck engine would. I'm no expert on it but it looks like a tall deck engine anyhow.
also, you'd probably need to modify the truck harness to work in the fbody. I didn't find a carb'd manifold for it on my quick search so either you're modifying a harness, or making a manifold.

 

okay so the trans attached isnt a t56 i haven't looked yet. And from what I can tell the engine will fit no problem. I found some youTube videos on how to wire up a 350 small block I think it should be similar for the 8.1. So if the trans doesn't fit I was reading that a tremec would be a good choice

 

Yeah the truck trans has little prayer of fitting. The bellhousing pattern makes transmission choice wide open though.
I've found tall deck big blocks in these cars but they're all drag only cars, so the engine compartment is no frills etc.
I don't think it'd be my choice for a swap but good luck!

 

I would not encourage undertaking this swap. At best the 8.1 was rated at 340 HP - lots of torque, yeah, but not much for power. The weight penalty of a tall block all-iron big block is nothing to sneeze at. Fitment will not be easy. Don't expect much aftermarket support for the swap, you're going to be pretty much on your own doing the wiring. Figure on investing in HP Tuners so you can get into the PCM programming to work with your older platform.

There are much better and easier ways to achieve 340 HP. And cheaper. But, it's your car, your time, and your money, so of course you're free to do as you please.

Oh, for the record, I've done a few 3rd gen engine/transmission swaps over the years, and own a 2004 Avalanche 2500 (8.1l) with 198k miles.