Thought I would post the answer, to my own question for someone that might be searching the archives.
Although the Ford chassis service manual does not indicate any point to attach the tethers to, my local dealer suggested we order two tether kits for Ranger. The parts were no longer available for the 94, so they ordered in kits for a more recent model. The tech that was going to install them for me @ no charge but was on vacation the week they came in.
I picked them up, with some other parts I ordered. Opened the package to check the instructions to see if it was something I was willing to try. Six screws to remove the rear cab interior panel and I was pleasantly surprised to find the 2 tether attachment points clearly marked on the sheet metal. The newer model clips fit exactly. All I had to do was drill two holes in the interior panel for the bolts to pass through. Everything took less than
1/2 an hour from start to finish, and looks like a factory installed option.