Heres some pics of the rear framerail I made myself, using 2x3 by 1/8 steel tubing, I am changing the whole floor, and so decided to change the framerails in this area, its overkill, but well worth the time and effort

Here is the frame mocked up, think those welds will hold??

Heres the what I used as a template, the old framerail and "torque box" cut out, I have never done anything like this before, and with no option to buy a new rail, I just cut it out, and kept my fingers crossed.

Heres the difference:

This is what I want my car to look like, one day!
