plymouth barracuda stuff

Its not a pale yellow colour is it by any chance?

Righty, most Mopar cars are 5x 4.5" HOWEVER many A body Mopars (Dart, Valiant, Barracuda, Duster, Demon, etc) have the "small pattern" hubs. These are 5 x 4" and are a sod to get aftermarket rims for. Also a lot of A bodies have had disc brake and rear axle upgrades which inlcude a conversion to the normal 5x 4.5" PCD. So its always worth checking if your car is in any way modded.

Also also also be aware that Mopars often have right handed threads on the wheel nuts on one side. This is to help prevent them loosening in service however if you don;t know this you end up trying to undo them and you are actually tightening them...

Even worse is on an upgraded car where parts have been used from multiple donors you may find a mix of left and right hand threads - a mate had this on one of his cars which had a rear axle upgraded by a previous owner...

Your chose of wheels are the factory oprions for the A body or custom ordered aftermarket ones. You occasionally find seconnd hand wheels turn up in the small pattern but rare as anything. Also unilug wheels do not fit them as most unilugs are either 4.5 - 4.75" or 4.5 - 5" slots.

On a '66 I would say the best looking combo is the stock steel wheels with the povo spec small hub caps. Rallyes and Magnums also came in 4" PCD (5.5x14 and 6x14 sizes IIRC.) but again these are pretty rare now and command good money.

not the one from Dave Madders then?