Rear axles puzzlement

I inherited new axle boots and u-joints with my parts 240Z. In the course of pulling the u-joints, I caused or discovered some damage on the inside mating surface of one yoke. I had an extra set of axles and decided to go ahead with those, but found that the end nearest the diff is permanently sealed - not held with a spring clip etc. Of the various manuals, the factory shows the whole thing as being a simple project (remove with a soft-faced mallet, etc.), while Humble glosses right over it. Clymer is confusing in that in one paragraph it says you can't do it because there are no replacement parts available, then in the next goes on to describe how to do it. A peek in the Black Dragon catalogue shows they have remanufacatured replacement axles, but only for 260 - 280 automatics (at $900 a pop! I'm building a Datsun guys, not a Lambo ).

What I'm guessing is that the sealed-end axles I have are really for a later model automatic. Sound right?

Now, with respect to the damaged yoke -- and here I'm talking about the small piece, not the end that is part of the axle -- does anyone think I will have any balance problems using one from the A.T. axle?

Thanks, as always