I read somewhere there is a 68 DT1 only forum, I have looked and can not find it. I just purchased a 68 s/n 10323 and have some questions and looking for a couple of parts. 

Were you thinking of the "Badges" forum?

No it said 68 only group was up and running. It is on this first page of badged bikes referring to 68 DT1 's and is on about page 10 of the thread.

Some of the most knowledgeable experts on the 68 DT1 are on this forum... I'd go out on a limb and say THE most knowledgeable experts in the world on the 68 DT1 post here. 

So go ahead and ask your questions.

One of the parts that is missing is the chain guide, it seems this is a 1 year only part and chances of finding one could be slim. Also do the tach and speedo use the rubber rings around the tops like the later years? And also looking for the horn and headlight hi low switch. Mine is broken internally and Deet said they are not repairable in that shape. I have a few people looking for the switch but so far no luck. My 70 AT1 has the same switch so I guess they used them for a few years on all models.

The bottom chain guard?  2 bolt?
let me look for it, will be later on in the day.
Are you in the States?

What size it that rear sprocket?  WoW! Can you even use 1st gear?  

Lower chain guard for a 68 is single bolt.  If you have one laying around I would be interested if priced fairly.

Yes and I am in Texas

That is being changed out. Never started it yet as I started a restore as soon as I got it.