I used my stock drive shaft without modification. I did have to put a new yoke on the trans end to fit the T5.
I put one in mine and used the stock driveshaft with no modifications. Was an automatic and converted it to T5.
I had a 3" custom made by The DriveLine Shop. All new parts and spin balaced, $200 delivered to my door.
I have a stock 1990 5.0 Mustang drive-shaft. Way stronger than the stock one. Exactly the right length.
Interesting replies ... in the article that they just did in Car Craft, they cut the stock Mav driveshaft 1", going from a C4 to the T5. You want to be sure to have some room for the yoke to move into the tailshaft as the suspension moves up and down. You never want that to bottom out, but don't know the spec off the top of my head.
i used a stock 5.0 mustang driveshaft which worked well with the stock ride height with a 6 3/4 rear end, but when i lowered the car and installed the 8.8 i had to have 1 inch removed from it to give the yoke enough clearance so not to bottom out against the tail housing on the transmission
I set mine to 3/4" out with the car sitting on the ground. A bump will move the rear upward and push the yoke into the tranny.
I had to use a stock fox body 'stang shaft when I converted over to the SROD (same dimensions as a T5) The Mustang shaft was an inch shorter then the Mav shaft. The yoke was basically bottomed out in the trans with the stock Maverick shaft.