They're 1/2-20 thread...even the Dana 60s, but I always change them to 9/16-18. Dorman # 610-278 Application is a 90s model Ford Dana 60. Drill the holes out to 39/64 and tap them in with a hammer.
If your rear axle is the matching Ford axle, then they're both 1/2-20 and I'd probably leave them unless they look crappy. However, if the rears are 9/16-18, I'd change the fronts to match as they are FAR more common.
Any 8 lug wheel will fit the 1/2" studs, you just have to get the right lug nuts. That's the pain in the ass part.