Mine started as a 1978 D-200 crew cab long box. Original d-code 440. I converted it to four wheel drive and a 12v Cummins / 518 overdrive. 3.54 gears and pump tweaked way up. Gets about 15mpg empty. A good working converter or a 5 speed would really help. Maybe in the near future.

Vinny
Pics
http://s726.photobucket.com/albums/ww269/vinnyb/1978%20Crew%20cab%20CTD/