Alright i had set aside the input end steel flange for the rag joint, that came with the remanufactured box figuring i wouldn't use it. Its got 15 splines across about 1/2 its circumference, and smooth near the pinch bolt side. Must be 30.

Found a... 3/4"DD x 3/4"-30... listed universal on Borgesons site.

Hmmm, this may help convince me to know exactly what my rig has , before ordering a replacement/upgrade part in the future...