5.3, 6.0 & t56

[Blue666]

I am currently planning my build to include either a 5.3 or 6.0 Vortec Engine. I also want a T56 trans with a forward mount shifter. I am not sure if I will be able to find the engine & trans together in my price range but need to know if there is any difference in the T56 or bell housing used behind either of these engines? Are they fully interchangeable?

Also, the T56's that were in 1990's vehicles, (LT-1, LT-4) would these be fully interchangeable to either a 5.3 or 6.0?

Thanks in advance.