If you look at 65-66-67 BSA Hornets and the offroad spitfires (I have a few unit A65s and one of my keepers is a 68 Spitfire with the UK style cafe tank) they used a breadbox type tank,, some call it the bread loafs.
(interested in a unit A65 project?? Im downsizing,, what year would you like?)
But I have a friend who went to the UK back in early 1980(s) and visited Lyta and I have a whole stack of photos of the shop, as well as many tanks he made. Many of them were for bike friends back here in the US and Dave ordered a whole pile of them (About 10-12 tanks total) of different styles. Dave was into all kinds of British bikes from Vincents to Manx, to Goldies and had a shop, and later married into the famous Langlitz leathers empire. But at one time all kinds of people were making tanks,, I know several who learned the trade in the British car industry and known to make some tanks. As well a few US guys as well, We hosted Evan Wilcox at our museum for a class on Tank making and metal work.
(Evans bikes/tanks have been featured on the cover of Cycle world and many other magazines and he designed the body work that ended up being used on the Norton VR880 vintage rebuilders and then the Norton American 961s and still used by Norton UK today)
Heres a period Lyta tank, a 1967 BSA Hornet and the man himself in his small workshop in Blighty circa 1981.
**Note,, as most are likely aware,, this style tank came in both fiberglass and alloy from BSA. I have had 441s, with them as well. Clearly the one on this bike is alloy with paint on most of it. I am really not sure what it is, other than commenting it appears similar,,
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As to the Yahoo groups, I admin several and member of several others. Much discussion, but I can post some material to educate people, I am researching the options and likely will migrate the ones I admin to the new service instead. ** Note,, when these first came out circa 1999-2000 it was EGroups or something like that, briefly owned by someone else and not sure what date Yahoo took them over. the value of uploading files and pix cannot be overlooked, But I understand they juggle and intense data load by doing so. Clearly the revenue is not there without clogging it up with ads and malware. The issue is the new platform, hopefully more stable costs.. allegedly $100-110 USD per year. So looking at options. Many people I know wont and refuse to use Facebook, One vintage club I am in, I was a organizer-vice president was taken over by another guy and everything migrated to Facebook. Many of us were left in the dark.
The irony is,,, the people on FB tend to think everyone should conform to the Borg and cant understand why not everyone thinks the same.