"Some" Lincolns had an odd output shaft with three (or so) splines but nothing in the Ford line had it. Not a source for a CJ iron tail housing.
Yes, three on the C6's, 1966 to 1969/70?; but only two with the MX transmissions, 1961-1965. The large square recessed reliefs in the shaft and slip sleeve accept a rectangular insert housing a row of needle bearings, this engineering exhibiting only a rolling verses the greater sliding resistance otherwise practiced, thou at a greater monetary cost; and permitting the least amount of resistance to the movement in the relationship of the transmission an drive shaft assy's; therefor assisting in providing the occupants of their "land yacht" the smoothest of rides as one traverses the unappreciated bumps in the road.

Also realize there is more than one cast iron tail housing for a C6, and only one (that I know of) being for the CJ.

Scott.