A quick but big update. First off, the rear window is fully installed! Not much fun, but it had to be done. Second, the gas tank is installed behind the seat, but not yet plumbed to the engine. Three point seat belts are fully installed, including cutting the seat frame to allow for passing the buckle side through. Lastly, the seat frame, bottom and back are installed in the truck. I've still got a punch list for inside the cab (e.g., door cards, handles, headliner, floor liner, etc.), but it really looks like the inside of a truck now! For the first time ever, I climbed inside, sat on the real seat, not the folding camp stool, and fired up the engine! It was very gratifying. But...no rest for the weary! Off to the truck level punch list.
The first Pic shows the layout for the seatbelt pass through. I used the ideas from Phak1 and Grigg. I marked the frame where my seat belts were, added an inch on either side for margin, measured for buckle height and made my cuts and bends. The second Pic is with the seat installed.