www.express-builder.com

Any thoughts on why they call out 2" square shoulder belt hard points, then give dimensions to cut out the foam that are actually located at solid laminate areas?

Not sure why they call that out, but my first and oldest Wheeler has bolts with big washers for the seat belt attach point. Mine are behind the solid area behind the pilot and off to the side of the passengers. I used a retractable seat belt that works in any position and mounted it overhead for the shoulder belts. If you try to put it through the UNI, it will weaken the structure and it will be very difficult to do. For reference, the shoulder attach points are about in line with the front of the back windows, but close to the radius of the fuselage. You drill a hole in the inside skin the size of the washer and dig out the foam. Then fill the area half full of resin fiber mix and press the bolt in with the washer. Make sure the head of the bolt is surrounded or it will turn when you put the bolt on and it will drive you nuts. After you get it in the hole, finish filling the area around the bolt until its flush with the inside.

PUT TAPE AROUND THE THREADED PART OF THE BOLT TO KEEP THE RESIN OFF OF IT OR YOU WILL KICK YOURSELF LATER I PROMISE !!!

Any idea who makes your retractable? recommendations?

I can look it up later when I get time, but Summit racing has several, Jegs, and others. Ebay also has a lot, just look for the ones that have a DOT certification tag on them.

Any idea on best lengths?

The lengths are standard, I think around 120 inches. Sounds like a lot, but I had to mount my reels on the top of the plane to make it work, which means an inertia reel that will work in any position not just straight up vertical.
I first mounted the reel on the lower half of the fuse, ran it to the top like your car, and then back down to the side of the seat. 40 inches up, 48 back down and then across the lap and oops not long enough. Mounting it high works.

excellent idea, thanks.. I will start looking for them..