The old fuel tank was sufficiently corroded that I purchased a new one, but when taking the old one out it was interesting to see that it was a two-part unit. I haven't found this in the manuals. The old fuel tank was a replacement from "Mr Fuel Tank" in Toronto as some point. The tray on which the tank itself is very nicely made, and so looks as if it may be a Land Rover part, but I can't be sure.
The old tank would have been held in place by the filler and vent lines alone, which somehow doesn't seem safe. The new tank is the more usual one-piece bolt in unit.
(Edit: those that know indicate this is most likely an error, as the two should indeed be attached.)
Here's both parts:
The underside of the tank:
The underside of the supporting tray:
