Something i found on the net though its refering to the use of these transmissions in a factory five cobra kit car the info should still be good for anyone looking for a new one so injoy ppl...
"NOTE: The information contained in this document is a collection of information from a number of sources. It serves as a starting point towards choosing a transmission for your Factory Five. For information that may be beneficial to add or correct in regards to this document, please email email@example.com
For Factory Five Racing kits it is suggested that if the engine being installed is below 300 horsepower (at the engine) then a T-5 would be the best choice due to durability and weight considerations. If installing an engine with more than 300 horsepower (at the motor), than it is recommended to install a Tremec TKO 500 or 600 transmission. Keep in mind that the transmissions are being installed in 2200lb-2400lb. finished cars, unlike their often compared counter part, the Ford Mustang, which is approximately 1000lbs heavier.
Transmissions used in Mustangs
-A 5 speed manual transmission that came in 1983 ½ to 1993 5.0 Mustangs.
-Also came in 1994-1995 V8 Mustangs though the input shaft is approximately ¾ inches longer than the earlier versions. This causes the need for a longer bell-housing. The driveshaft needs to be shortened ¾ of an inch to the specifications in the build manual.
-Easily attainable in the aftermarket for $900-$1100.
-Very light (70-80lbs), reliable, and strong for its weight.
-Manufactured by Borg Warner until the mid 90’s, then began to be produced by
-Fits Factory Five Roadsters, Spec Racers, Hot Rod, and Coupes as a direct bolt in.
T-5Z -Same as T-5 but has a 2.95:1 ratio first gear that makes it slightly stronger
-Only available from Ford Racing #M-7003-Z
-A 5 speed manual transmission that came in 1996-98 4.6L V8 Mustangs.
-Similar to the T-5 though its mount interferes with the chassis cross member in MKI, and MKII kits. The MKIII will allow the T-45 to bolt right in with a 4.6L Motor.
-Production bell-housings were designed to mate up to the 4.6L engines.
-An aftermarket 5 speed manual transmission that also came in 1995 Cobra R Mustangs.
-Stronger than the T-5.
-The old version of the TKO 500
-Uses the same clutch and yokes as the T-5. 10 tooth splined input shaft
-Shifter mechanism is different than the T-5, but this transmission has the ability
to install a mid mounted shifter.
-Fits Factory Five Roadsters, Spec Racers, Hot Rod, and Coupes as
a direct bolt in with ¾ inch tall spacers underneath the rear mount.
-A 5 speed manual transmission is only available in the aftermarket.
-Same case as the Tremec 3550, so all mounts are the same.
-Uses a different clutch than the 3550, and a different driveshaft yoke. 26 spline input shaft, 31 spline output shaft
-Mid mounted shifters are an available option.
-Fits Factory Five Roadsters, Spec Racers, Hot Rods, and Coupes as a direct bolt in with ¾ inch tall spacers underneath the rear mount.
TKO 500 can take 500lbs-ft of torque
TKO 600 can take 600lbs-ft of torque
Tremec TKO roadrace or close ratio
-Same as the TKO except that it has a 0.82:1 ratio 5th gear rather than a 0.68:1
ratio that the 3550 and standard TKO has.
-A 6 speed manual transmission that came in 2000 Cobra R
Mustangs, and 2003/2004 Cobra Mustangs, as well as Dodge Vipers, Chevy Camaros and Corvettes. This transmission is basically a very strong TKO with a 6th gear.
-Does not fit solid axle Roadsters with SBF/BBF because it is too long, which will cause driveshaft bind. IRS cars avoid this problem because the driveshaft does not travel vertically. The longer wheelbase Coupes and Hot Rods also avoid the problem because the driveshaft is longer. 4.6 powered cars will work with a T-56, due to a overall shorter drivetrain length.
-Rear mount interferes with the rear chassis cross-member in MKI and MKII Roadsters, Coupes, and Spec Racers.
-A modern automatic transmission that began to be installed in Ford production vehicles after 1983.
-Same length and mounts as the T-5 transmission.
-Strength is moderate.
-Customers have installed this transmission. They have had to find a way to attach the gear selector to the FFR kit.
-Ford began to use an electronic version in the early 90’s called the AODE.
-There is a large quantity of aftermarket versions and parts available.
-A 3 speed automatic transmission that came in Ford cars such as Galaxies, Mustangs, Torinos, Falcons, and others in the 1960’s and 70’s.
-Strength is moderate, though can be built to be very strong.
-Customers have used this transmission, installing it on their own. Possibly needs
transmission mount modifications and gear selector mounting to be determined.
-A 3 speed automatic transmission that came in Ford cars such as Galaxies, Mustangs, Torinos, and others in the 1960’s and 70’s.
-Extremely Strong transmission.
-A very large transmission. Significant modifications would be necessary to
allow its fitment into any Factory Five kits.
-Not recommended for a Factory Five kit.
-A 4 speed manual transmission manufactured by Ford that 1965 427 Ford Cobra’s, Mustangs, T-birds, Fairlanes, and other cars of the 60’s and 70’s used.
-Will bolt right on to the stock mount in all Factory Five kits by drilling a hole in the center of the chassis mount. The shifter mechanism and handle installation would need to be custom made. Some custom modifications would also need to be made to work with a cable clutch linkage.
-Shifter linkage is externally mounted on the transmission.
-A small transmission, though very strong.
-Came with short and long tail shafts
Richmond 6 speed
-A 6 speed manual transmission sold in the aftermarket
-Customers have installed on their own.
- May need modifications to mount for installation into a Factory Five kit.
-A 3 speed automatic transmission with overdrive that came in 1979-1983 Mustangs.
-Very weak transmission.
-Not recommended for a Factory Five kit.
-A Borg Warner 4 speed manual transmission that came in some 1960’s Mustangs
-Similar to a Top-loader.
- An upgraded version of the stock T56
- Fitment in Factory Five cars is unknown"