What follows I posted on Sept. 13th in response to another inquiry about transmission selection. I'm not 'up' on all the TREMEC numbers. The T-5Z will work for your application, my understanding is that some newer T-5 application units will not. I'd call Modern Driveline.
The T-5Z has a lot to be said for it. What follows is a small piece of what is presented on the Modern Driveline web site in the 'Tech Alley' section labelled 'T-5 History'
________________
The "Z" Spec T-5 "In 1993 Ford started offering a new service unit to the Ford Motorsport crowd. The nick name T-5z comes from Ford’s part number, 7003Z. This Ford Motorsport T-5 is also sometimes referred to as "World Class T-5". While it is a Word Class T-5, as it has all the upgrades, having a 2.95 first and “Cobra pocket bearing does not make it “World Class”. The T-5z is a 1993 Cobra T-5 with 2.95 first gear set and .63 over drive. It has the best of everything. Hardened gears, short throw factory shifter, steel front bearing retainer, and tapered output shaft bearing and a seven tooth drive speedometer gear. Best of all it has a torque rating of 330ft/lbs. based on 100,000 mile usage. The stock T-5Z can handle up to 450hp with a soft locking clutch and is not shock loaded like in drag racing."
________________
NOTE: The T-5Z 5 speed transmission weighs only 75 pounds! Also, IF you look at the Modern Driveline web site, you'll see that they also offer the option of a .73 overdrive ratio or a .59 overdrive overdrive for an additional charge. The .63 5th gear overdrive ratio is the standard TREMEC offering.
________________
A four speed or five speed transmission with the right rear end gearing will change the driving enjoyment of your y-block! With my tire size and 3.56:1 gears, I opted for the .73 overdrive ratio T-5z Modern offers.
I hope that pointing you toward the Modern Driveline web site is of some help.
NoShortcuts
a.k.a. Charlie Brown
near Syracuse, New York