Same size for 1, 1.5, and 2 ton, probably same as 3/4 ton too?

When you get new ones drive them with a hammer and punch, then install lock washer and nut and tighten just a little more than necessary to squish the washer.
Same trick works on kink pin lock bolts.

They seem to be soft enough that they break before pulling home with the nut, so set them with a hammer and punch, don't try to force them with the nut.

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-