Swapping TH350/203 to TH350/205

[SilverMiner]

My 1980 K10 Suburban has the original TH350 mated to the original NP205 t-case. I am also the proud owner of a 1978 GMC Jimmy which has a much newer and built TH350 mated to the original NP203 (converted). I'm going to be doing an engine swap soon, and I'd like to put the better TH350 out of the 78 into my 80. Both are currently installed in their respective rigs so I can't count splines. Is this a straightforward swap, or are there differences between these otherwise identical transmissions that will prevent me from mating either one to the other transfer case?

Before I start this project, I'd like to know if there are any parts I should pre-order or search for in the junkyard. Both vehicles are operable and running, so I know I don't have to search for adapter plates or that sort of thing. I guess I'm most concerned about whether or not the input shafts are different.

Thanks for the assistance