302 w/ 3spd manual, convert to T-5?

There are tons of threads on this subject, and websites too.

The short answer is that you can use a T5 bell from about '94 or older, or the '71 bell with a CNC-machined aluminum spacer. The newer bell pretty much won't work with the old Z-bar, so you have to go hydraulic or cable.

I believe the 3-spd should be a "3.03", which refers to the distance between the centerlines of the output shaft and the gear cluster.

Here are some webpages about the T5 swap copied and pasted from my Bookmarks folder:

http://www.darkhorseperformance.com/
http://www.moderndriveline.com/index.htm
http://www.g-forcetransmissions.com/productoverview.asp
http://home.austin.rr.com/cobra2914/tremec.htm
http://www.drivetrain.com/driveline_angle_problem.html
http://mustangsandmore.50megs.com/Pages/Tremec.html
http://www.geocities.com/2bav8/5speed.html
http://www.mustangmonthly.com/howto/41438/
http://www.mustangandfords.com/techarticles/5272/
http://www.sacramento-mustang.com/Newsletter/T5_Swap/t5_swap.html
http://www.5speeds.com/t5/
http://www.mgwltd.com/mustang_shifter.html
http://www.gt350clone.com/
http://www.geocities.com/2bav8/t5data.html
http://www.fordmuscle.com/archives/2000/09/t5swap/index.shtml
http://www.dvsrestorations.com/mar05.htm

one correction to 180's info, you want a bell housing from a 93 and earlier 5.0 as the 94-95 bell is deeper requiring the later T5. the next thing you have to deal with is the shifter location. the stock truck shifter comes up from the top of the trans, where as the T5 shifter is located at the rear of the trans, just about where the front edge of the seat is located. two things you can do;

1: find a 4spd that will bolt up in place of hte stock 3spd

2: swap the ford T5 tail shaft for one from an S-10 T5.

You don't need a new bell for that swap. All you need is a bolt on transmission adapter (about $150) to mate the T-5 to the existing bell and modifying the crossmember to move it rearward. The driveshaft may or may not need shortening. Keep the flywheel, pressure plate, clutch, clutch linkage, etc. as is (although, it would be a good idea to put in new parts since you have it apart anyway.)

Bolt the adapter to the bell, slide the transmission in, bolt in the crossmember.

The only real issue will be the shifter location. A Mustang T-5 places the shifter at the tail of the transmission and may be too far to the rear. The S-10 tailhousing moves the shifter forward and may be better for a truck application.