??-----Just looked at the 1968 model listing.----It shows a MQL model.----That would be the long shaft model.----Easy to convert a short to long with a kit.----So yes , they are somewhat rare but they exist.
The cover is plastic.----Plastic is not a permanent material.----Easy fix with a new cover.----The electric primer valve was a wonderful item first came out in 1980 and could not be improved in my opinion.
I believe that air pressure is pumped to the main oil tank.----That pressure keeps the small oil tank full.----When motor is not running air pressure is bled off via that open fitting that goes nowhere.