Sounds like the seal's not in all the way. It isnt flush with the step in the bore... it's deeper. No need to spend more cash. Us a smaller diameter socket and drive the seal in farther.
Just make sure that whatever you use to seat the seal JUST FITS where the seal is suppose to go. If you tulip the seal by using something that is too small in diameter, the seal will leak.
One more thing to check. If you have a power lok posi, make sure the centering block in the differential didn't come apart. The centering block on a factory power lok is a three piece item. It the center pin wasn't peened when the diff was assembled, it will come apart and not allow your axles to seat, causing exact problem you seem to be having.