What will a stock GT drive trane handle

The tranny will take more than it's rated for. The differential is pretty stout with 31 spline axles. I would say anything over 500-525rwhp you could be asking for trouble. Mine is at 490rwhp (mustang dyno) and it's had some seriously hard launches with Mickey ET Streets at about 4800 rpm's at the track. Haven't had any problems or noises to speak of. I've had the tranny out a few times and have not had the input shaft twist at all. One thing to note is the stock clutch is a total POS! Also, don't believe the stories about how weak the motor mounts are. Haven't had a failure yet.

i have run my car for 17 k miles now with abour 100 quarter mile passes and at least 30 over 500r whp on slicks and have not hurt the trany or rear end

i made 6 passes last night at 575 rwhp with 28x10.5 slicks leaving at 5000+ with a 1.46 average sixty foot and did not break anything

the STOCK DRIVESHAFT however you need to ditch imeediatly before putting on sticky tires.