hey i am looking to buy a 2005 ford 6.0 dully with a zf 6 i think its called im not sure if these tranys are any good ?? if so how much hp can a stock one take the truck has 170000 km on it

 

They're really good. The trans itself can hold quite a bit, probably need a clutch upgrade with really hot tuning, but beyond that they're pretty stout. It's a pretty common trans, it was used in a bunch of trucks. Duramax's used them too.