A couple of relevant posts:
https://www.retrobike.co.uk/threads/show-us-how-you-fixed-crack-on-manitou-fs.379748/page-3#post-3003616
https://www.retrobike.co.uk/threads/7005-head-tubes-cracking.492709/#post-3723211
There may be more.
Is the blue frame still available? If so, I think I know what it is and if so my friend had one I built for them which was then stolen. I'd love to do a project to rebuild it.
If frames are being dropped in Worksop I have friends there who would be happy to keep it in their garage until I next...
Good spot! Hmm, that's interesting. All The T## numbers I know of are steel frames with the stamp on the BB shell and a two digit year code, so either it's a different factory or completely different format for aluminium frames. Any insight @sam_white ?
I was tempted to bid on this and start a discussion later if I won, as I love an oddity. However, I have no space for more bikes at the moment. To try to avoid ending up with it, I'll out it for discussion here:
https://www.ebay.co.uk/itm/116712584954
Thoughts?