Suburban 2500 manual transmission swap

[Oifla]

Hello all,

New to the forums and Chevy/GM but have been wrenching for a long time.

I'm searching for a 2500 Suburban. I know I want a 3/4 ton and I'm looking for a 1996-2006, meaning my search spans two generations. My plan is to eventually install a 5 speed transmission (NV4500) (I am not a fan of automatic transmissions)

Any reason to choose GMT400 over GMT800? I'm finding as many (meaning as few) of one or the other and the mileage numbers don't seem to vary too much. From the perspective of the future NV4500 swap, any reason to choose one over the other? Thanks

O.