If you mean this
Pinion Counterbore The pinion bearings were the same from 1937-1954 therefore the Pinion Bore is the same size from 1937-1954.
Group # 5.447 Front bearing
part # 954780 double row
Group # 5.484 Rear bearing
part # 125630 single row This one has a little bigger diameter.
However there were some improvements made in the early 1950's on the front bearing
Close style cage vs. Open style cage The truck axle is made of a heavier construction than the passenger car axle.
Read Here Under >
Rear Axle Assembly, 1/2 ton and 3/4 ton trucks>
Pinion Assembly---1/2 Ton Model>
Axle ShaftsTorque tube diameters changed a few times from 1929 and up. I would think that the 1937-54 would all be the same as they all use the same ball and the front skinny part of the torque tube were all 2". The rear half was increased in size from 2 13/16" in 1950 to 3 1/4" in 1951. This was done to "raise the fundamental frequency of torque tube vibration. With this change, vibrations from other sources no longer combine with that of the torque tube, over a narrow speed range, to produce a peak vibration point which was encountered occasionally in the past".
1/2 ton Rear axle cross section Toque tube rear axle exploded GM 1/2 ton axle overhaul Film strip slides 1/2 ton truck axle uses a
Oil Retainer passenger car doesn't.
The purpose of the pinion bearing oil retainer is to slow the flow of gear lube into to the axle housing,
which helps to maintain a bath of gear lube on the front pinion (thrust) bearing.
Maybe they sent you the wrong bearings.
Why are you installing new bearings?
