I have just completed a frame-off resto. on a 70SS 4-speed. Both my rear trans seal and pinion seal leak,after driving just a few miles. I wish that this could be just coincidence,both seals being bad,but I dont think so. I checked my wheel base on both sides and there is a inch difference. I've yet to check my pinion degree. The drive shaft and universals are new and feel tight.Is the inch difference on the wheel base too much, 111-3/8" driver and 112-3/8"passenger,If so do you think this would be the source of the vibration? Thanks John

I wouldn't think the difference in wheelbase would cause the vibration problems, BUT if the WB difference is caused by the rearend control arms or a bent frame, then possibly the pinion angle is off, and this could definitely cause the vibration problems you mentioned...

I would guess the pinion angle, but if everything is new/refurbished and stock (restoration), then maybe somethings bent...

As for the seals leaking, even if the pinion angle was off, I would think it would take a lot of miles to cause the pinion seal to go out. The pinion gear itself is positioned by two bearings, and as such, it and the pinion yoke shouldn't move or wobble enought to cause the seal to leak even if the driveshaft is out of balance (or vibrating from the incorrect pinion angle), unless the pinion bearings are really bad.

The trans rear bushing and yoke (if installed far enough on) should also not wobble enough to cause a leak... A worn bushing or too-short a driveshaft could cause this...

As for the wheel base, I would measure the rearaxle centerline from a reference point on the FRAME (and the rest of the car), and not to the center of the front wheels. The front wheels could be staggered slightly front to rear... You want to be sure the rearend in perpendicular to the chassis/body when driving...