You have made quite an improvement already , True there is a lot more to do but making a first step is the biggest , seems the the truck body is all thats left to hold the remains of the rear arches in some kind of shape as said if removed they would crumble to dust , barely anything to try and tack weld together no matter what gauge steel you try , like trying to hold bits of aluminum foil with scotch tape / cello tape I guess you'd say .