I already have one, but this may be something I bet you can get a LOT of people interested in, even if it is a VERY low cost item.
There is a hose barb fitting that people use to do the "scuba mod" that we mount onto the FJ's rear diff. It uses a Toyota Camry “Union” part number 90404-51026.
I'll bet if you got bunch of 'em on hand you could get a lot of "visits" to the dealership to pick 'em up!