I have one and I'll sell you either it or the bridge itself at a good price! LOL Seriously, need more info; there was a British arm in the old days which claimed to be based on Isombard Kingdom Brunel's original tube bridge design, Zeta, Rega??? There have been several arms something like you describe but most of them were in the 70s or 80s. Couldn't have been a TriPlanner [sp.?] could it?
unique tonearm Brooklyn Bridge
A few years ago, an audio shop in Northern New Jersey was selling a tonearm that looked like a strucural bridge element, anybody know who made them and perhaps where to buy one?