i think you should get more feedback on this, i don't know much about this, but there is a kit from standard transmission that includes the (crown) nut mentioned previously, and a different shaft that keeps you from having problems. I know you definitely need to replace that nut, and i know if my transmission was apart, i would replace that spline (shaft) also.
I am trying to decide whether to do my clutch also (i think i would get the south bend) and replace the parts in the transmission as well. . .