Lug pattern for the 400 series 1/2 ton 2wd trucks and SUVs (C series 1500s) is 5 on 5"; other vehicles that have this are fullsize GM cars( Caprice, Electra, Olds 98, Cadillacs). Also the older GM truck, 2wd half ton, 71 through 87( 88-91 on SUVs). Some Lincoln cars in the 70s used this pattern as well, there's a couple of 15"x6" factory aluminum wheels that Dad found to use on our smaller trailers.
In my area the 10 spoke aluminum wheels, like my Burb has are still fairly plentiful. But yeah, 235/75- 15 tires aren't as common as they used to be. I may go with a different size when I buy the next set of tires....
As stated above, a slew of GM full size cars had that size, however most were steel wheels that needed hub caps.
Though I saw a sweet truck at a car show with 17's from a rear drive Impala SS.
Skip trying to find a factory application. Check with aftermarket companies. They've already figured out what fits with proper width, back spacing, and diameters in excess of OE offerings.