Of the Model 128 Equatrorial 2,4" scopes there were quite a lot made and sold over the years, and are relatively 'common'.
However, the 65M model seems a lot more rare and thus very rarely advertised for sale.
It is a bit unclear to me when this specific model was first introduced, I have a Dutch brochure from 1983 specifically mentioning this variant, D 65mm and F 900mm on Equatorial mount, and even so listed as model 128 Polarex. It was even specified specifically listed as 2,6" i.s.o. 2,4".
Note that the much more regular D 60/62mm models also had that designator, both for Unitron and Polarex. So the 65M did not get a specific / exclusive model number.
I've also seen a 65M for sale about 5 or 6 years ago in Holland, and the seller stated that it was from 1975 and had a Nikon lens (dark blue coated).
I'm wondering the use of Nikon lenses was specific to this particular model, or was it used in other 2,4" variants aswell?
So it seems that this particular model was introduced at or around 1975 and was also still available in the early '80s.
How rare is this model currently in the US?
In Europe/Netherlands I've only seen this model for sale once or twice over the years, so I feel this must be an extremely rare variant?