the 5.3 will bolt up to the t56, it is the same block as the 6.0 that is in the vette. I just goot done doing the swap on my truck. if you look for the 5.3 that was out of the SSR or the suv's they have the alluminum heads and block. they are the easyest motors to work on Parts are cheap, and in a small z they will get good mpg.