1.5 x 1.5 x 1/8" angle. I removed the rear cross brace and bolt in piece for spare tire.

I put the angle on the inside of lower frame rail and weld it to frame. the tank had pre-drilled holes in the tank flange.

I was thinking of 1x1 square tube to raise it a little in the frame rail but did not have help test fitting the bed so I went to bottom of rail.

it works out as there is a little room on top of tank to help get at the rear frame/bed bolts. (I think? I will be doing that today.)

I looked at takes from there but I went free shipping.

works good so far and I try to hook up gauge today as well.