Thanks popeye! I purchased the roller bearings and compared new to old with dial calipers. I will be replacing at the same time as drive tire. The race also has the indentations in the race that you mentioned. Are there other components I should be checking that may have been affected by prolonged use under these conditions? Is the replacement procedure for the race just to drop out from the bottom and bolt in new? Anything I should be on the lookout for?

Small pry bar or big screw driver between roller and drive unit. To much movement and they need changed. You will also want to check for indentations in the race were the rollers normally ride when steering straight