I have a 85 F250 4wd.I have run into a problem.I have a set of 15inch wheels with a new set of Swamper TSLs. The wheels bolt up on the rear just fine.When I tried to bolt the fronts on, the caliper and bracket hit the inside of the wheel.My question is, can I swap a set of 1/2ton calipers and brackets onto this thing and get away with it? If not what can I do to use the 15in wheels?

Grind your calipers until they fit.

If you have 6-bolt spindles you may be able to do something like this:
http://ford.off-road.com/ford/article/articleDetail.jsp?id=198393

I would look closely at what sort of 15" 8-lug wheels you can get your hands on. Seems like everybody has has different results - and that's within the Ford context.

My J20 8 lug hubs drop perfectly into my 4.5" offset steel 15 x 10 wheels. No grinding required. I was pleased as I also thought that I'd have to really cobble up something.

The size of the J20 rotors and calipers are exactly the same as the J10/Waggy 5 lug size, only it has 8 lugs.