Early Style - Bolt From Behind Rally Caps

[Ironhorse]

Have seen reference to these from time to time but never as a full set of four previously. As in the title, there is no provision for bolting these thru the front of the cap to the wheel. They bolt on from the back of the wheel using a 1/4-20 NC bolt or screw head fastener. Not sure which, these came with a mix-mash of bolt head, common and Phillips head fasteners. Good bright shine on all but also all have some condition issues such as dings, nicks with some loss of the chrome plate. Hard to get decent pics of chrome or stainless. One is missing the Chevrolet bow tie emblem, other three emblems are present. When did GM change from this style to the more commonly found caps with the 5/16'' bolt thru the front of the cap?

Any thoughts on value of these for posting to the parts forum are appreciated. Not show quality but good 10 footers for a cleaner no bolts showing look to the rally style wheel.