You aren't gonna pick up a diesel in decent shape for 7500 Paige, if you do look at Ford's beware in the diesels, if it doesnt have the 7.3 in it dont even look at it, you may find a 6.0 powerstroke in that price range but it will be a money pit for sure, known for having motor troubles that can cost up to 10,000 to fix.
A 4 door chevy or ford would fit the bill nicely but not sure if you can find one in your price range.