Just an update for anyone interested as I am ready to reassemble.  The folks at Standard Bearings, 959 33rd Avenue SW in Cedar Rapids, Iowa were able to cross reference some of the original numbers for seal and bearings once I got it disassembled.  The part numbers are-  C/R 17653 Grease Seal and  ZKL6207ZZC3 Radial Ball Bearings.  Hope this helps some of you tearing down this Belt Pulley Drive assembly and trying to rebuild.  By the way you need an 1 13/16" deep socket to take off the nut, it will be "staked" from the factory, check the outer surface of the nut as it may need to be built up @ machine shop or a sleeve put on to create a sealable surface against your new seal. It, the nut not only holds things together but forms the surface to which the seal rides. Hopefully this will keep "smelly" 90 Weight grease from leaking out on to your frame and wheels.