[pfilean]

If the Slim Jim is toast anyway then it makes a lot of sense to change to something better. Slim Jim had a 3.50 first (and the better HM was about the same) so it could get off the line with the 2.XX rear ends. The TH400 will not be as good and needs a 3.xx something rear end. You might also consider the 200 or 700 OD transmissions and still change to a 3.42 or 3.55. You will still get a good first and with the OD retain a good highway gear. With a 64 block you don't have the adaptor and starter problems. Get a BOP flanged 200 and it may be a lot easier. Either 400 200 or 700 will have some floor interference problems but those are solvable.