NAPA does list a 10-inch clutch (found using a 1958 3100 as a vehicle.)
LINKIt doesn't say how many pressure plate bolts it has, which is critical if it's going to fit on your flywheel. As Rusted nut says measure the worn area on the flywheel, or alternatively, from the outside diameter of the flywheel to the outside diameter of the pressure plate (the part that actually contacts the disk.)
Attached are pics of a 139 tooth (6 volt flywheel) showing the 13-1/2 inch diameter (not including the ring gear teeth), and the diameter of the polished area where the disk runs. This is an 11-inch clutch flywheel with 9 pressure plate bolts. So if you measure from the edge of this flywheel to the pressure plate, you'd find that dimension as 1-1/4 inch.
