ive been getting a vibration in my truck when im doing between 60mph-75mph. i had my tires balanced and rotated but still didnt fix the problem. the problem started right after the motor swap. if i go WOT i dont feel the vibration but if im just cruising i can feel it. i was thinking maybe the driveshaft was the problem. anybody got any suggestions?

 

Your drive shaft could be out of balance, or possibly a u-joint is going bad...those would be my first guesses.

 

did a road force balance vs a free wheel balance right? i didn't realize there could be such a difference till I had it done myself.

 

anybody know of a good shop in houston that i could take the truck to to have the driveshaft checked out?

 

I will be curious to see if you can get this resolved. I have the same problem. I did my engine and trans swap and have had the vibration from 60 up since. I have had my tires rebalanced, truck aligned to account for the lighter engine weight, front driveshaft shortened and balanced with new u-joints and the rear shaft balanced with new u-joints, raised the rear back up 2" by swapping back to the original hangers and I am still looking for the solution. Also, checked my driveline angles and they are good also.
Good luck I can't wait to hear what you find.

 

the vibration i had was 98% eliminated by installing new front hubs. gm has a tech service bulletin that states if your truck was built before january 1999 and wheels/tires are correctly inflated and balanced then the front hubs should be replaced to fix the problem and if the truck was built before april 99 then the leaf spring bushings and shackles should be replaced as well. your truck being newer may not have these problem but you might check 'em out just to see. I couldn't tell the hubs had anything wrong with them until i had removed the tires and rotors and turned the hubs by hand and could hear a dry grinding sound inside.