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

[andrewmp6]

This might help you http://67-72chevytrucks.com/vboard/s...d.php?t=116639 and if you need any parts http://offroaddesign.com/catalog/transfercaseparts.htm

[Redcap]

All TH350s are 27spl male. This should be as easy as splitting the 203 off and bolting the 205 on. Should be real straight-foward.

[tommartin]

just wondering also, what about the adaptor. does that have to be changed? My NP203 had 7 bolts, and it looks like the NP205 has?

[Redcap]

Yes, you will need to change the adapter as well.

[SilverMiner]

Thanks everyone for the good info. I suspected that this was going to be as straightforward as you all said, but I was confused by reading too many threads on other boards. I think the problem was most fellows are swapping out a 203 and replacing it with a 205, and on the CK5 board they are all doing doublers as well, so the correct info I was looking for was masked by all of their issues.

Thanks again!