Spoked autos use a 17inch rear rim and a 19 inch front rim. These are identical in size to the 77/78 750 K bike rims but they are aluminum rather than steel. You would need the spokes specced for the autos or the 77/78K bike inorder to use the rear on earler the bikes that came with 18inch rears. The spoked Autos rims are indentical to the rims from the 75/76 Gl 1000s (17" rear, 19" front). The GL pieces will be much easier to find. . . . .