The original roller bearings with the spirals seemed to have survived very well as long as they were properly lubed. Apparently, there is not much pressure on them when in service.
About 90% of the differential overhauls I do, I find the original seal and race Henry installed when the car was new. The seals are always shot, but the bearing race is usually in good shape. Definitely stay away from the repos.
Attached is how I go about replacing both.
http://www.santaanitaas.org/wp-conte...-race-seal.pdf
Tom Endy