What is missing here? I do not see in parts listing a lens cover or something other than a complete unit. 68 DT1 by the way. 

Lens was only available as part of the complete assy .
68 Blue lens assy's are as rare as " rocking horse s**t " .
Good luck with that .

later 1968 DT1's came with the red indicator but I don't know when that started. you might want to talk to Enduronut as He is the 1968 DT1 expert. he was a huge help when I was building my 1968 DT1s. neither one of them are accurate due to the rarity of parts but my early 1968 came with some rare parts like the front axle, tool box, original exhaust tip which I traded to Enduronut years ago. probably some other parts coming to mind, I have original front forks for both and the early fork boots are different than the later 1968 forks.

my later bike which is vin # DT1-100xx had a red indicator in it and I am sure my very early 1968 DT1-02xxx rolled out of the factory with a blue one.

yes, the blue ones as well as the red ones are as rare as Hen's teeth. near unobtanium.

speaking of which there are many running changes between my early 1968 and the later 1968 DT1.

these running changes make restoring a 1968 DT1 accurately difficult and costly if you find all the correct parts for your bike in the production run.

 

I have a blue one somewhere.

those both red or red and blue? if you are selling them or one of them, let the OP get them.

Speed & Sport has the part your looking for #18. Only very early ‘68’s had a blue lens and then they were charged to red.  I don’t know if the VIN # of this change was documented as I haven’t seen it noted in the several ‘68 parts guides I have.  

 

Hey Dave, those are both red, I have to dig around for the blue one.
may sell

my serial number is 10323 so it was probably red then. Forgot to look at Speed and Sport.

My early Parts Guide shows the part # as 214-84101-60-00
The Speed & Sport part # is 214-84101-61-00
I’m assuming that the -60 is blue and the -61 is red but no VIN # Is displayed when the change was made.
My buddy’s ‘68 is a 7XXX VIN while mine is a 13XXX VIN and both are red…

That item on all European models of the period was blue. However, I don't know if the early DT1 part is physically the same as the later items. Photo of my 1975 RD125 item attached.

Shouldn't be too difficult for someone to manufacture and then cut/punch to size some semi transparent blue plastic material for the lenses?