BAttitude7689

ok currently i have 98GT motor and tranny (auto) and im in the middle of swapping in a 2003 motor and tranny (auto). i did my research for what i need on the motor swap. I plan on using my 98' wiring harness and 98' computer. now my problem is.... will my 98' harness and computer work with the 03' tranny. the reason i ask is because the 03' tranny is control thru the computer for the speedo and my 98' i have a small black gear inside the tailshaft of the tranny to adjust my speedo correctly because i have 3.73 gears. i looked inside the side of the 03' tranny and dont see a gear on the shaft to grab onto my speedo gear to control the speedo. will the speedo work correctly?? will the tranny even shift at all because of the difference?? i really need all the help i can $$ is tight and this my daily driver. please all advice would be greatly appricated

teej281

Use the tranny out of the 98. The 03 tranny is electronic speedo which is controlled by the computer. The 98 is a mechanical speedo and has the gear to control the speedo. So just swap the tranny out or buy an 03 wiring harness and do that swap. MY suggestion would be to use the 98 tranny.

BAttitude7689

yea that would great if only the whole reason i am doing the swap is the 98' transmission took a dump and dosent work any more, so that is no longer an option, i do have the engine harness from the 03' motor. only thing i dont have it the computer and the interior harness for the instrument cluster. so i was thinking would that be an option and would it all work?

BAttitude7689

would i need to re-pin my Transmission Range sensor?

BAttitude7689

1998 Mustang GT (Auto) swapped to 2003 Mustang GT (Auto) *Motor and Transmission* currently using the 1998 computer and harness

just cleaned up and we had to roll my car out of the shop, but the motor fires up just fine, but now here is the issue

on the left side of the transmission (towards the middle) there is a sensor, my mechanic said it was some type of transmission speed sensor. now with sensor from my 98' inside the transmission it would plug in of course because im using the 98' wiring harness and computer, but with it inside the transmission it would not allow the output shaft to turn. so we removed the sensor and put the 03' sensor in the transmission and the it turned just the plugs were completely different plugs.

what are my options? list my possible ones if you can? if i cut the plug off the 03' harness and just solder the 2-pin connector to it then i can use my 98' harness will that work? if so will it work correctly?

now with the extended rang speedcal from dallas mustang...would that fix my speedometer problem? im kinda confused with all of this so could you just help explain it out a little for me with this whole swap i have so much stuff running through my head im gettin confused some so that would be great!! thanks alot again for all the help! i really wanna get the car running and driving and shifting properly ASAP

Alex821

I'm thinking about doing the same. So is it possible to just swap the my 98 GT motor with a 04 GT motor and keep my 98 transmission?