Hy guys, I did some research on these "U" joints, I came up with some part numbers from different suppliers. Joint at transmission, 4spd. Republic p/n C1910, Spicer p/n 288-1X, GMC p/n 3609288 or 3689288. Joint at transmission 3spd. Republic p/n C1710, Spicer 302-13X, GMC p/n 591646. For all the other joints in the system, Republic CB1350A, or CB-R55, Spicer 5-7X, GMC p/ns 609515 609948 2186972 2186973 2230781 2450093 3708931, I don't personally understand why so many GMC numbers cross to the same part but thats what I found, I hope it helps you guys somewhat.