Re: 1994 aerostar
If you currently have a 4 speed, stick with a four speed. It all comes down to the wiring harness for the transmission, and if it will be compatible with the PCM (central vehicle computer). With it being a '94, you shouldn't have too many problems but again, going from say a 4 speed to a 3 speed probably won't work. Going from a 3 speed to a 4 speed could work, but I'm just guessing on that one. Perhaps one of the transmission guru's will post up shortly.
'11 Ram Quad Cab 4x4 SXT 5.7L HEMI (stock); 48,500m
'06 Pontiac G6 GT 3.5L 220hp; 64,000m
'12 Chrysler 200 Limited 3.6L 283hp; 28,000m
'99 Taurus 3.0L 2V Vulcan 145hp; 154,300m - Traded
Amsoil in all vehicles!