I have a leak on my pinnion gear ( 1978 Pace). The rear end was redone in June 2002. Question is can I redo the pinnion seal with out removing the rearend from the car, all the other axle seals are fine.

Yes you can. Remove the drive shaft, the pinion nut, and yoke. Mark the pinion nut and keep track of the turns when removing. Pry out the old seal, and tap in a new one. Reinstall the yoke. Reinstall the pinion nut to your original position, and tighten it another very small amount, no more than 1/16 turn. This sets the pinion bearing preload, and is critical.
If it's overtightned, the pinion bearings will fail. If it's undertightend, the pinion bearings will fail.
If you can't turn the nut, just block both rear wheels and the diff will hold still, and the nut can be turned.

Ken Styer