55.2-59 1959 rear bumper brackets, inside or outside of frame rails?

[nikwho]

Hello all,
Dumb question, but I'm curious if the bumper brackets go inside or outside of frame rails. I would assume inside, but that's simply an assumption. Ive got bumper brackets, but my bumper is a few days away.

The reason that I am asking is that when I installed fuel tank between my frame rails, I wasn't running a back bumper. For safety, I welded a 1 3/4" DOM tube between the frame rails, to protect the fuel tank in the event of a rear end collision. So, I'm going to have a LOT of grinding ahead of me, if that tube has to come out! I would also have to remove the fuel tank for said grinding to take place.

In fact, if the brackets are indeed supposed to go inside the frame rails, it will probably be FAR less work to modify the brackets to run them on the outside. Any one know? Anyone have photos of how the brackets install? I'd like to start work now, so that I can be more or less ready to install the bumper when it arrives!