I've got a trans with the same problem. I just want it as a spare but I wonder if something like a speedi-sleeve used on crankshafts is available. Mine only moves about 1/8" back and forth so the front bearing may be OK (I hope). I think if the shaft is real loose the front bearing is toast but I'd like to fix mine if I can. I believe Chicagao rawhide makes the speedi sleeves but have no link or phone. If you could find one that is the right diameter for the pilot bushing, couldnt you turn the rear shaft and file the end until it slips over the input and go from there?

I'm going to try this later but now I'm welding in patch panels so it'll have to wait-------------------------Hank