They should be snug, when clean you should have to push them in by hand, and they should not fall out on their own.

The shims are OK, that's to take up the slack and variation in the axle end and the thrust bearing.

You may have more than one oversize pin choice if needed.

Grigg

•1951 GMC 250 in the Project Journals
•1948 Chevrolet 6400 - Detroit Diesel 4-53T - Roadranger 10 speed overdrive - 4 wheel disc brakes
•1952 Chevrolet 3800 pickup
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"First, get a clear notion of what you desire to accomplish, and then in all probability you will succeed in doing it..." -Henry Maudslay-