I have a ten bolt on a 69 skylark. The seal in the housing is leaking diff fluid. I took the shaft off in order to replace the seal..... but I can't get that dang but nut off. It's 1'1/4. Plus the gears turn while I try to loosen the bolt. I found a way to keep it still, but that nuts just won't budge. Any suggestions....
You need to get a piece of angle iron/steel. I use a section of an old bed frame side rail.......about 3 feet long. Measure the distance between the two hole openings for the U-bolts. Transfer that dimension to the steel rail and then drill the holes for them slightly larger than the U-bolt diameter. Now, get two bolts with nuts to attach the angle iron to the pinion yoke. Now, have someone hold the rail while you use a breaker bar with 1.25" socket to break the pinion nut loose. You can also use an air impact gun to break it loose. When you reinstall the pinion nut, you will want to set the pinion drag torque to 10 to 15 inch pounds. Use a torque wrench to check this measurement. If you are not comfortable doing this, take your car to a rear axle shop and have them do it.
