From SM465 to th400 with NP205

[sandking]

First of all, and I did search, but need some clarification first.

The vehicle: 1972 Blazer with the SBC 350, 4-speed, 4wd, D44 up front and 12 bolt in the rear.

OK, I know I have the SM465 and the NP205 because I researched the casting numbers on them. But I keep reading about things I am not sure of like, figure 8, 32 spline, 10 spline, round, 8 bolts, 6 bolts, etc. These are all Greek to me

I want to swap the 465 for either a th400 or a th350. How can I properly identify the parts I have? I need to know exactly what I need to do to make this happen. What kind of adaptor is needed? The cross member is not an issue, I can make it work. I read that the front and rear drive shafts need to be lengthened and shortened, is this right? I am assuming the th400 is longer then what I have now. Is this process just a matter of pulling the tranny and adaptor, then replacing with the new and having the drivelines done?

Thanks in advance, Joey