OK, sorry, I didn't read it fully.
I do (now) remember having to modify the bracket a tad, but can't remember how!. It fitted mine, whether I used it with the Truck Cab or Hardtop!
Must be honest though, it was a few years ago, so the actual parts and numbers may have changed, I just looked at Paddocks website as I know that's where I got them from 'cos I used to live only a few miles from Matlock and Paddocks.
Maybe you need a fabricated bracket, might be worth seeing what a local independant might have or come up with. How do newer Defender truck cabs have their belts fitted? Might be a chance to modify or even use as is an anchorage point from them?