Transmission swap

[reddogg]

I want to install an automatic transmission in my daughters '89 mustang,2.3. The transmission in the mustang now is a 2 prong connector, the one i wanna install is a 3 prong. Can I splice the wiring or do anything to make it work? Can I change the valve body inside of the transmission?

 

[bhuff30]

hmm, it's been a long while...
but as I recall, the 2 wire transmission has only an electrically controlled lock up for the torque converter. The 3 wire transmission has an additional wire for the 3-4 gear change, upshift only I believe.

If you installed this transmission and correctly wired the torque converter lock up and the ground, then the transmission would simply act like a 3 speed transmission, never going to overdrive. You could drive it forever like that, with the only penalty being gas mileage. If you want to make the 3-4 shift work the only option I can think of would be installing a switch to force it. Of course, the difficult part is knowing what the switch should do... You may just need to ground that extra wire when you want to make the 3-4 shift.