Hi Rob and Steve. Thanks for the replies. You know, I might have been a little hasty with the initial 'butt ugly' appraisal, 'cause its hard to visualise how it could look......
With a little further digging, I turned up this
......."This tank was on my 1984 BMW R100RS Limited Edition and hence the pearl white paint. The bike has very low mileage and the tank was empty most of its life. It is being sold with gas cap and two BMW petcocks as shown in photos. It has never been damaged and the paint is much nicer than the photos indicate. This Hein Gericke tank was available for /5 /6 and /7 motorcycles. It holds 36 liters. It was designed to fit BMW's with stock seats and fairings without any modifications. It installs easily and sits over the seat. It was manufactured by Hella Light Company in West Germany. It is the only non-metal tank to pass the rigid German Police Code (TUV). It is made of Cyclovac unbreakable plastic". My friends guess that it was a Hella tank, may have been a good one!!
![Image](http://i.imgur.com/25Ft7XE.jpg)
It is pretty boxy, but I'm seeing a few pics that has the tank looking OK......
![Image](http://i.imgur.com/L31Pqec.jpg)
Hmmmmm!!?