68DT250,
You're probably already aware that original 68 tank frame mount is circled in blue.
Very nice bike!

 
 

 Here are a few photos of my pucks on my 68 DT1 from restoration disassembly, and if you look closely you can see the tank pucks are bolted to the frame.  Frame and Engine SN match.  I bought my bike from the 2nd owner who purchased it when he was 16.  
 

Any sources for those bolt on tank mounts?

No, they were on the bike when I picked it up from my buddy. I have looked several different times but with no luck.

There’s been one on eBay recently for $299 and others as high as $599. Crazy $$ 

   That’s really interesting…… the bolt on brackets look very well made …. would Yamaha have actually manufactured them or are they more likely to have been fabricated by a skilful metal worker?

I recently posted about the tank stay as a new project came with a much simpler stay but still with a manufacturer look ….. the bike being in the first 1000 off the production line.

Bart what is the first vin number of the bike with the bolt on cups for the later tank?

cheers T1

 

I think it was DEET that once posted about using suitably sized automotive engine "freeze plugs" to replace damaged or missing tank puck brackets.  Notch a section out of the rim. 

While I am by no means an expert on all things ‘68 DT1, my research (which includes several original Parts Lists) indicates that Yamaha never produced a “bolt on” bracket to accept the newer rubber puck style fuel tank.  All Parts Guide notes and Service Bulletins discuss the need to change the complete frame to accept the new style tank. That said I have seen several creative bolt on / welded on modifications to early ‘68 frames.  Here’s a pic of my late ‘68 frame which shows the factory updated mounts. 

 

 

Somebody make those and sell them !