[Motor City GMC]

Has anyone had any luck finding step rails that mount to the frame and NOT the body?
I have a 79' K30 with a 6" lift and 37" tires and my ol lady and kids have a hard time getting in and out of it, so i want a set of these but i just dont like the idea of mounting them to the backside of my rocker panels or wherevrr they mount to the body, but am havi g a very difficult time finding any that mount to the frame, especially because of the outside mou ted gas tanks.
Any suggestions or pics of yous would be appreciated.

Here is a pic of the style i like