I would avoid saying anything about the VIN lists being only for US models or mentioning the color at all at this point.

Do you have the Yamaha VIN list vs the "Forum" copy?  Enduronut's version is arguably the most accurate in the world but Yamaha's document should carry more weight and will support your position.

If you wanted to add more info than VIN...  then I would consider adding service bulletins on tank mount and two-bolt ignition cover with pictures of your bike which further support it being a mid-production 05XXX 1968 model year bike...

If color comes up...  not sure why it would...  but if it does, then pull out the other docs. 

Important thing here is to keep it simple and concise in my opinion and the VIN is most solid proof and a couple of other unique 1968 features that Yamaha documented in Service Bulletins should make it clear to anyone that this bike is pre-71.

One more thing is that Yamaha USA has been known to provide dating letters to customers.  You could try that as well.

Hey MarkT   Looks like my full doc did not get posted because it is too big.   So ill do it in pages 
     

  

 

Here's the Service Bullitin for the change in gas tank mounting method which occurred during the 1968 model year on all production after VIN # DT1-13000. 

Part 2 of the tank mount modification would be the lack of what is shown as "tank holder" on your frame.  You might want to remove the tank and photograph this area of the frame.  

Another piece to your puzzle. 

thanks

UPDATE

I think I am close to getting my bike ready to pass this inspection.  The dealer finally agreed that my bike did not come with signals and hence as per the regulations as I pointed out to him I am good to go on this issue.       Thanks guys for you help on presenting my case on this issue....

The only thing I need is a front head light 6V bulb (which I have a spare) and a rear sprocket see photo.  I told him that I had another dealer look at my sprocket and said I should replace it, but that it was not a critical safety issue.  Thoughts?   I am being told by the inspecting mechanic that he won't approve the inspection unless the existing sprocket, which is worn is replaced .   

I have been looking to find a sprocket for my DT1 to replace it and it has not been easy.  It does look like from a the Yamaha parts list that the part number for these sprockets are the same from 1968 - 1972.   Does anyone know where I can get one of these parts and if the compatibility is correct as it appears that after 1968 it is easy to source for those years.   Number of teeth is not a big deal for me, but the lower the better.  By chance will a CT2 sprocket work?

I've check the forum of details on this and I am not sure I understand some of the discussion.

Any help with this would be appreciated.    Getting close to taking this thing over the finish line and on the road again, .....

Thanks everyone for you help on this. 

Congratulations!

Yes, that sprocket is worn out.  Best to replace both sprockets and the chain as a set when you see wear like that or any old parts used will quickly destroy the new part.. 

Thanks for your help MarkT.   

Any thoughts on where is a good place buy a chain sprocket kit.  It seems like a tough part to find and I've tried calling a few places already.    

Luke.  

Mark is right, it's hammered.

Getting two new sprockets may be a bit of a chore, as I've noticed over the past year or more, there are some parts for our beloved bikes that are becoming scarce!  You need two things:
1. Use Yamaha's online parts catalog to search part numbers. Widen your search to other years, the basic parts for '68-'73 are somewhat the same.
2. Plug the part numbers you find into eBay. 
Be patient, get a cocktail, and start searching. You'll find what you need.