They are 8 on 6 1/2. That was for the longest time the standard bolt pattern for 3/4 tons. So there are wheels out there.

One thing to watch out for is the later model wheels have a much deeper backspacing or positive offset. For example the 5 spoke Ram truck wheels, 17s, are standard 8 on 6 1/2. But when I tried to put them on my truck the positive offset pushed the wheels so far in that they rubbed on the upper control arm on front and wouldn't go past the lip on the brake drum in back. I eventually solved the problem by installing new upper ball joints with flat hex capscrews, and grinding the lip off the brake drums.

I could have used something like a 1 1/2" spacer but getting them machined was going to cost around $400, for correct material American made spacers.

If you look at all the modern trucks you'll notice the wheel centers are quite close to the outer edge of the wheel.

R.