as for the tranny it all depends on how hard you are on it obviously. no tranny is gonna hold up with all that power and getting hammered all the time...as for head studs i made it to 120k miles and had it chipped since 8k and for the last year had been running the higher hp tune from dfuser(well the highest he would tune it without studs and things for reliability on that end) but i got studs put in and he gave me a wicked tune and truck runs great im at 127k and on the stick clutch thats soonto change but you get teh idea its all in a little preventative maintenance keep the fluids changed egr clean and filters goin and you should get lots of miles and fun out of it