I actually had a set of 74 belts (from a Scamp) that I had gotten, same as the 75 as far as I know. My 73 had no "box" in the back panel either. Rather than try to cut into that area and try to weld an anchor point, I thought it would be simpler for me to buy the aftermarkets and use the anchor points I have. So I still have the 74 belts if anybody wants them. I will take some pictures of my setup today or tomorrow, and post or send them.