Bill,
I had the same problem, with after-market brackets, and an original bumper that had been straightened. I installed the brackets on the truck and was unable to get the holes lined up to the bumper properly to place the bolts, while on the truck. Worried about bending things and having something let go and scratch my new paint I tried a different approach. On the bench I loosely attached the brackets to the bumper (with no problem) and then attached the brackets to the frame (also, with no problem).
I have no idea why one method worked and the other different.
How did you try to mount them?
Kent
