They are both lq4's and the white silverado runs. It didn't run when I bought it though. It had been in a roll over accident. So it turned the manifold into an oil pan.

I took the spark plugs out and cranked the engine by hand first. It was exxon valdez all over again. Oil gushed out of every spark plug hole. Then i cranked it with the starter and got the rest out. Replaced the air filter and cleaned the maf with maf specific cleaner. Put the plugs back in checked all the fluids and started it. It ran the first time. I haven't seen so much smoke come out of a car or truck before. HAHA!

As far as the sierra the manifold is cracked and all the accesories are smashed into the block. Im betting that it will run with some work. I already have an ls6 manifold and f-body front accesory drive. Things should swap nicely.

As far as the sado front end do you guys think it looks better than the sierra. The tail lights are busted on the sado though. Im not sure which one I like more but the logical choice is to use the sado front end. I will thrash on it this weekend and see what happens.