I've seen skinny Cragar wheels without the unilug dated as late as 1982. Yes, the chrome was not that great early on. Don't recall right now when it started being done in Mexico. Anyone have a set of them for a point of reference?
These wheels here i never dismounted, but suspect the caps were simply put on by a previous owner from a newer set.
I've also owned unilug wheels that were dated 1978, and they were 15x8. If I knew this, then I forgot it now, but when did the unilug start being offered? I know early ones had an aluminum insert. Have a few, just don't have a pic handy.
Those caps you posted seem to be great examples of the early generation. No "R" and the blue color is lighter (and not as consistent) as the later ones.
For a while, I was on an acquisition grabbing as many of those as I could. Lost count after 2 dozen. Despite what the part number reads, be careful of what you buy. I've had a few which did not like to fit the old wheels. Ended up splitting a few when I tightened the screw. My point being that they can be NOS for a reason- like poor fit.
Although you can't see the dates on the wheels when tires are mounted, I still like the sets I have dated form 1969 and older. I'll try to post a pic of dates tomorrow.