I need some expertise. I did a 14ff swap a couple of months ago on my 91 Suburban. I've got a couple problems. When I left off the throttle over 60 mph, I get a vibration and hum coming from the rear. U joint is new in the rear. I've read about a couple different causes, driveshaft and possibly pinion bearings or pinion angle. The other problem is the right rear tire. I've thrown the wheel weights off twice and now I've got a leaking axle seal. All axle seals and bearings are new. I don't know if they're the same problem or I have two things going on. Any help or advice is welcome and appreciated.