the can of worms is now open!

[1969 GMC]

today I took the T221 and adapter off my truck (gosh it was a PITA...the "hidden bolts" under the inspection cover of the adaptor drove me bonkers). however, much to my dismay, when I took the adapter and coupler sleeve off, I found that the splines on the out put of the transmission were pretty well worn. Also the coupler sleeve was almost smooth inside on the transmission side. I am attaching some pics, what can I do about this? I do happen to have a spare 4x4 SM465 in the garage, but I don't really want to swap trannies unless its the only thing I can do (i'm working in my gravel driveway...tranny jack = not move). I do know the spare SM465 I have is very low miles...was told this by the p/o, and the output shaft and the NP205 coupler sleeve arent worn at all and look brand new. any advice? thanks...