BMW R GS R80G/S R100GS. Large alloy petrol fuel tank. Paris Dakar style. Used
Aluminium'Paris-Dakar' style petrol tank for BMW R80G/S, R80GS, R100GS and derivatives - probably any model airhead (at your risk) but it certainly fitted my R80G/S as shown in the last photo. Tank only for sale, not the bike! Holds 7 (maybe 8) gallons; beautifully made, a work of art really, and very light. Internally baffled (see photo inside filler neck); two tap threads - one tap off your old tank and it will come with the extra tap and T-junction needed.
You'll just need to figure out a means of holding the tank down at the back (see photo). It's got some minor dinks and scrapes from fair use which just adds to the patina - I'm sure you can embellish them, with a story outside the local corner shop, about how you've just got back from crossing the Kalahari last week, did it on one tank-full too!
NOT a common item and rarely available; feel free to ask questions - remember, the only stupid question is the one you don't ask...... As a random final thought - I'm looking for a 350 Jawa, just in case you've got one lurking in the hedge.