Ditching the TH400 for a NV4500

[JCampbell]

After burning up the TH400 in my '77 1-ton and having the Sub sidelined w/ a mysterious issue w/ it's TH400, I'm seriously considering swapping all my rigs over to NV4500 trannys. I'm going to use the '77 1-ton as the guinea pig seeing as how it's currently just a bare frame on the side of the house and if all goes well there, I'll move onto converting the Sub.

What I'm looking for is hints, tips, tricks and advice from those who've done such a swap. Things to look for, specific/desirable tranny years/serial numbers, possible fitment issues, floor modifications, crossmember relocation, etc.

Thanks in advance.