Vibratioin at 30psi and around 1300 rpm

[DKenworth]

Well, i think that it could be also a input shaft on tranny where the carrier bearing seats, I would not reccomend to bump up engine HP and torque, maybe only up by 25HP. Cause ur mpg will go down for sure, and a lot more stress to ur engine head, pistons... clutch... I think theres a difference in heads for 485HP or 500+HP. ( I Wwould love to hear what RAWZE will say about this) Well, now u can start from drive shaft bearing under sleeper, check if there is a not a lot of play, that is cheap fix. If not this than its going to be ur carrier bearing or imput shaft.