They were specified for my 2003 Ford F550. I could only do them about 4 full turns and they stopped. I checked the themes and they match. I even ran a 9/16" die down the length of the bolt just to clean it up. It feels like the nuts are constricted inside. I figured for $40 I'd just put them on and see what happens. Once they've gone further, they're much easier to take off and put on. I expected them to break but not yet. I have a 40 gallon 120 psi compressor and I have to let it build pressure for every nut! I'll let you know once I've driven the truck and checked for problems. Update: Most rusted after only 4 months.