how do i identify what tranny i have? 01 gt

 

if you look on the door you can see the build date. there is a site that tell the dates of the car sin 01 that has the T-45 and cars that have the 3650. i belive its stangnet or corral that have the dates.

Also if you go and look at your water pump there are two different ones. one for a 99- early 01 and one for late 01-04. The early one has a longer snote on it as seen below. the later one has a much shorter snote you can see beneith this other pic.

here is a 99- early 01 pump





here is late 01-04



So if you have the early style pump (one without the metal snote comming out of the pump) you have the T-45 if you have the later styler pump you have the 3650. I hope this helps you out.

 

There are 2 ways to find out
If your build date is February/2001 Mustang GT or later you have a TR-3650 NOT a T5/T45. Before that build date is T45. Build date is located on driverside doorjam.
OR
Check your driver's door for a sticker and look under "TR" for a "K". If you have a "K" then you have the 3650 Transmission. If not you have the T-45.

pulley-wise my stang was weird cus I have the t-45 transmission but the non piggy back style pulleys

 

which one is the better of the 2?

 

Between transmissions, most people tend to like the 3650 a bit more. It was developed for the Cobra R and ford realized that it was such a good tranny that they switched to it.