About the 510 bumpers, and being so dificult to get foreign(foreign to the US) bumpers for my 120Y/B210, and, being 510 bumpers so common(can be gotten new), I though about trying those in my B210(at Shasta last year I came about to that thought). For the 610, the front bumper might work , it is similar in shape, but the rear is another story, would have to brainstorm that one out, a rear 610 w/ a 510 bumper...perhaps.
I was thinking, the bumpers that came in the 610 with the big protruding US bumpers can be dismounted, gotten rid of the shock(bumper) and all the extension parts like the rubber behind bumper, and with homemade brackets, those can be installed as if they were pre 74(73 or earlier) bumpers, which look like the overseas version. The front 610 "bad" bumper does not have the signals on the bumper, but it comes with metal covers in place. The rear , though, has an area cut off for the shock extensions(rubber part), but that too, can be covered with metal, by welding a piece there, body working on it and painting the bumper, black, or , same as car.
Anyways, the 510 on 120Y might work too.
later._________________________