I have a Rodagon 80/5.6 and nope, definitely no ring came with it. How you mount it will depend on your enlarger I guess. I have a Super Chromega D so three lenses are mounted on a rotating disk, with each lens on its own mini plate. It looks like there would not be any space behind for a ring to sit, given that the disk must rotate smoothly when you need to change to a different focal length. It could be that some were sold with rings, but if the majority of enlargers of the period had threaded plates then perhaps it was down to the market. Anyways, each mini plate has a threaded boss, presumably for the most common sizes. For mine I found an M39 adaptor ring, (possibly off a dead macro bellows, I'm not sure now) and screwed that to the plate. The lens just screws into place, and stays there.