Bill - That race along side the outer bearing with the nylon cage is likely part of that replacement outer bearing set. They are after market original equipment type replacements for the original steel caged bearing sets, so a slightly different product, but that darker less finished surface doesn't ride on the bearing, so not of concern IMHO. These replacement bearings are commonly found in use in many of our old trucks and are also still available as replacement bearing sets today.
Finding one of those "plastic" caged bearings has surprised a number of Bolters over the years.
