Wow nice find! Those seatbelt placements in between the b and c pillars, and the one that is above cargo window look very odd. I don't doubt that they came from the dealer like that but I haven't seen another FJ55 with them. My retractable front belts are directly in line on the b pillar, and same with my adjustable rear seat belts which are on the c pillar (1978 model). btw if you ever want to let your front bench go let me know!
My US 1973 fj55 has the brackets for shoulder belts on the b pillar but no belt attached. It does have lap belts but I don't see how the shoulder belts would have attached...
simple is usually right... 1973 fj55