Here's the "lowdown." 8 lug Dodge wheels will fit from '61 on, unless Dodge has recently gone "German." Ford is pretty much the same, '60's on, as long as the wheels have a 6-1/2" bolt diameter. Duellies for Dodge are '69-'93. My '68 D300 originally was the last year for the 6 lug duellie, and it's '94 on, unless, once again, "German." The Dodge Duelie will fit the '67-'87 F350, with only one concern. The alignment pins on the rear hub are in different locations, bot most wheels have an oval hole to work on both trucks. These wheels are called coined lugcentric. "Volcano and crater," I call them, dimple and pimple. The load is transfered through the lugnut connection. The late model wheels are hubcentric, the wheels center hole fit tight against the hub, and flarenuts simple hold the wheel tight against the hub. Dodge's '94 and up fits Ford's '88 to '98, I do believe. Ford went metric with a larger bolt diameter, 170 MM, I'm running Ford 250 wheels on my '68 D300 with a '70 rear axle. Anyone with late model wheels will need to swap out the flarenuts for "old school" common lugnuts.