Did you get the complete hinges, or just the pins. You shouldn't need the whole hinge. Just the pins and bushings. The come out with a punch and hammer. Door hinges on the Fox Mustang are welded to the door shell and then the hinge/door assembly is bolted to the Fox body. Unlike a vintage Mustang where you can simply replace the complete hinge assembly, the Fox Mustang hinge requires the use of a cutting and welding apparatus to replace the hinge for major repairs.
I changed my doors too. I think they are welded to the door and bolted to the body. I had to pull my fenders off to get to the bolts. p.i.t.a. to hold the door up and get the bolts started. I had no one to help me.