Actually 6-lug wheels are pretty common, if you don't mind running non-original ones while you're looking for period-correct wheels. Virtually all the Nissan, Toyota, Mitsubishi, and other import truck 6-lug wheels run the Chevy bolt pattern. If you can find 15" wheels for an older Toyota Land Cruiser, they'll bolt on and look almost original, and there's a huge selection of suitable-size tires available. For 16" wheels, look into 6-lug plain steel trailer wheels. Just don't tell the seller you're buying them for motor vehicle use. (None of his business in the first place, but those wheels don't have the DOT certification for motor vehicles!)
Jerry
