For the past year or so my 1970 dodge power wagon has been having problems with the rear end. The passenger side wheel has been locking up when ever i try to go into reverse. I replaced the axel seals and replaced the brake pads and it still is locking up. I checked the parking brake and it was functioning as it should. I also tried pulling off the drum and trying without it on and it still continues to lock up so i'm assuming it is not a brake problem. the rear end is a 1970 Chrysler 10 bolt 1/2 ton. Any advice would be great.

 

open the differential and inspect the gears for chips.