Another Criterion RV-6 6-inch F/8.3 Newtonian reflector telescope on the Cincinnati, Ohio Craigslist:

http://cincinnati.craigslist.org/for/904079322.html
(I am not the seller of the telescope.)

According to the ad, the scope was made in 1975. This would be toward the end of the era for that classic telescope.

When did the last Criterion RV-6 come off the production line?