4BT to Mazda Trans
I am currently in the middle of a 4BT swap into my 72 Bronco. I have already done this swap into 1994 F150 and if you know how to weld and have coughed up the $$$ for the Cummins to Ford adapter on ebay it's really not hard. I'm doing a frame off restoration anyway, so with the body off this should be easier than some of the earlier conversions I've done.
I will be using the Mazda 5 speed transmission from a 1990 F150, like in my 94, just because a have a free one lying here. (I know I should not be stingy and just buy the ZF!!) The ZF adapter from advanced adapters will work on the Mazda tranny too and I already have the Dana 20 transfer case bolted to the 5 speed lying on my shop floor. The good thing about the Mazda trans is that it is easy to shift, like a car. Just a word of warning though, the gear ratios really suck. 1st and reverse are way high and 5th is kinda too low. My 94 F150 governs out at 71mph with 3.50 gears on the highway, uphill or downhill. I could never imagine using an np435. Too slow.