31-39 for the bearing?
33-46 for the retainer?
1931 to early 1939 used the 7109 ball bearing (1.379"OD x .593" ID).
Late 1939-46 used a roller bearing(GM part #142655, Hyatt#99004).
The retainer (GM #836713) was only used with the roller bearing.
(This roller bearing/retainer setup was also used on 1933-34 Standard, but this is a truck forum).
