[WADS56]

You can get any trans proshifted, and yes it is a pain in the rear to street drive but it can be done (I do it sometimes).
The Tko II has a stronger 3rd gear and a .86 5th gear while the Tko has a .68 5th. They both have the same input and output shaft. The Tko will hold your power output fine but the Tko II has a useable 5th gear(.86) not a econo gear(.68).
If you drag race your car most of the time the proshifted trans is the way to go. You can shift the thing above 6500 without problems and lightning fast. If your mustang is your only car don't get a proshifted trans you will tare it up on a daily driver.
Hope this helps,
Wade

I'm selling mine if you are interested.