There's a lot of guys in the 12s on T5 transmissions and lots of guys on here pretty deep into the 13's on factory T5s. Are these later T5s more durable than the mid 80s T5s that seemed to grenade often? I know they switched to the WC T5 in 89 I think. From my reading they seem to be stronger, and by quite a bit, is this accurate?

according to everyone on this sight the wc (world class) t-5s are a lot stronger than the earlier t-5s. the 88-92 t-5s are suppose to be able to handle up to 300 ft/lbs of torque. so yah they are alot more durable than the nwc t-5s. you can also upgrade the gears inside so they can withstand 500hp and 500ft/lbs of torque.

see yah

As far as power handling goes, the T5 is crap. I've gone through 2 world classes, annd a non, the world class is a little stronger handling 300 ft lb. If you run them right i.e. not power shifting, clutch dumping etc, they can last you quite a while. I'm running a V6 T5 behind my 350 and Haven't had any problems other than burning up a clutch, but I'm not super hard on it. I don't do clutch dumps and powershift. If I goes to the track I just take my time shifting as its not worth dumping a trans in a car I have to drive home once I get done. If you wanna handle some power, swap you in an old 4 speed and preferbly a tremec or t56

A t56 or a TKO would eventually go in...I'm just trying to get some ideas...seems like if you treat a T5 right you can get good use out of them. My buddy has 177k miles on his mustang original transmission. So thats good news and its an 1988 stang so it is a T5. I also dont drive real hard I just like to know its there when I want it