I would go into the links section of this site and call Jerry at Ag Parts First and check on the parts situation for the Clark front ends. 

You shouldn't need very many parts for them anyway unless they were really, really beat up. I would think the bearings and seals would be availible about anywhere. Our 1650 had well over 7,000 hrs of hard use at the time we sold it and we never put a part in the front end. My 1972 1955 has never had a single part fail in the 4wd unit.