[GMCNUT]

Here is a picture of the front factory wheel on Josh Quillen's (soon to be mine) 1960 GMC - it is the same as the light blue example above. 3 clips like a 55-59 wheel, but not the same as the 55-57 or 57-59 variations of the Kelsey Hayes wheels. This one has been observed (by me) on several 1960-61 GMC's as being GMC specific and apprears to be 60-61 specific. Chevrolet did not use this wheel in 1960 which was the last year of clip type wheels for Chevy - in 1960 Chevy re-used the 55-57 type like the Aqua example above. 1961 Chevrolet trucks were the first year to get the new "nub" type wheels w/ no hubcap clips.

There is some evidence to suggest that 58-59 GMC's also used the wheel you see on Josh's truck - I have not successfully completed my research on that yet - if so, that would easily explain why we see them on 60-61 trucks - a carryover item for GMC so to speak.