SM420 is shot

[odog]

Ok a couple of weeks ago, I went to leave work and the truck went bang. Has an SM420 tranny and a t221 tcase. Today I finally got a day off and pulled the tcase out. The output shaft on the tranny has splines that are worn to a knifes edge. The input side of the tcase has NO spline, they are worn off, I assume the final striping was when I heard the bang. So here is my dilema, do I do the NV4500 swap I have been talking about on my NV4500 will it fit thread, or do I find an output shaft for the tranny and an input collar for the tcase. I think the less expensive route may be to rebuild the sm420, but not sure. Any thoughts??? This was my daily driver, firewood hauler, but now its lawn art. Truck is a 1/2 ton 4x4 69 chev with 327'