I have found numerous complaints about blown spark plugs and rusted cracked manifold bolts on the ford 250 sd. The cost to repair my exhaust manifold on the drivers side could be as much as $1300 that's outside of the fact that I already had to repair the passenger side exhaust manifold. Some of the bolts are broken off too far inside the head and may require the entire engine to be disassembled to remove the bolts. I will never buy a ford product again. maybe I'll try Toyota