4:56 gears & R3 motor & 727 parts

mopardrew said
Spline on pinion rules out 742. Believe 489 is 29 spline? No idea on 8 1/4 or Dana 60. Spline count on pinion may help! Good luck!

489 is a taper pinion. 8 3/4 after market could be fine or course spline.
8 inch could be a Ford set.