Pretty much GM
Any year you find them on, they were used sparsely enough and on somewhat less common things like step vans and RV's and even pickups that you should not limit your search for any particular model or year.
Instead look for the wheels, don't get all worked up about what they come on so long as they are the wheels you need.
With some practice you'll be able to spot a 19.5" wheel in a junkyard from 50 paces.
Not all 8 lug 19.5" dual wheels will fit over larger rear brake drums, more about that here
https://www.stovebolt.com/ubbthread...wheels-and-drum-fitment.html#Post1311972As always test fit any wheel before deciding it is useful for you.
