I've never heard of ball bearings being use for differential side bearings (a picture in the 1947 shop manual Link) definitely shows tapered roller bearings. However, the front pinion bearing is a double ball bearing link with the rear pinion beairing being a roller type.

Kevin
1951 Chevy 3100 work truck
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1929 Ford pickup restored from the ground up. | 1929 Ford Special Coupe (First car)
Busting rust since the mid-60's
If you're smart enough to take it apart, you darn well better be smart enough to put it back together.