Shep,

Laughed when I saw your comment (Damned if I can tighten that top nut all the way )! Here's a tip. I added a similar backrest to my bike and the only tool I could find that would tighten that nut in the space available was one of those small wrenches that has the rachet built inside the box end. I bought one from Sears and was able to get a single click out of it on each turn. That made the difference for me.

As a side note -- I built a bracket that bolted to the three screw positions on the back of the cushion and welded a hinge to it. Welded the other side of the hinge to the support bolted on the fender. My backrest flops over on the seat when I'm not using it but when I sit on the seat and push back toward the rest it straightens up and gives me plenty of support. Sure makes those long rides a lot more comfortable.

pday