[aumoore]

Bill
You say you have a T-5Z behind a 351 stroked to 427 and it puts out 529hp and 470ft.lbs of torque? If so do not waste you time and money trying to change the 5th gear unless you just baby the car all the time. T-5's are ok behind a mild 302 but they will not hold up long behind a motor like yours. Put you money into the bank and save for a Tremec TKO and a good bellhousing.

My T-5Z lasted a few track events before third gear gave up the ghost. Third gear is a common problem with the T-5.

Or you could just order a Tremec with the 5th gear you want and sell the t-5 to a guy with less HP and Torque.

Trust me on this as I just put in a Tremec 3550 after my 267 rwhp/285rwttq 302 busted my T5-Z and I do not drag race. I was running on a small road course and it went on my second lap of the day.