Tadd, on T5's, I'm running one behind a (guessed at) 300 hp'ish 5.0. It's stood up to a lot of abuse. "However" It's never seen the kind of weight our trucks can put on the rear tires. I agree with Jerry, burnouts could be a problem. However T5's are easy to source and work on. In your' shoes if I already had one, I'd give it a shot, if it did fail, then look at other options.
On determining the ratio, the only way to know what you have is to read the tag (which you said is gone) and check one of the many online charts.....or rotate the input shaft and count the output shaft revolutions with the transmission in 5th gear. I'd go 10 input shaft revolutions while a bud counted the output turns. Be sure to mark both with a marker to make it easy to keep up. Divide the output turns by 10 and you have your od ratio.
Good Luck, RonR
Last edited by moparguy; 02/16/2018 2:07 PM.
