Helios 81 50mm f2 on Nikon mf body

[Neil Purling]

Are there variants of this lens that will NOT mount on a Nikon manual focus body and get infinity focus?
I wanted to avoid a mistake.
I have also encountered Helios 81's where the front element appeared loose and I saw Newton's Ring effect in the glass.
Is this a very common problem with this lens?

[Gurdie]

I think there is at least three variants:

Helios-81M 53 mm f:2

Lens made by Arsenal Kiev This lens was intended for the first series of Kiev 17. This first series used Minolta mount. A small number of cameras and lenses were made, Soon after they changed to Nikon mount. Source: www.photohistory.ru

So there are -81M:s with Minolta and Nikon mounts, I believe.

Helios-81N 50 mm f:2 (in Russian, the N looks like a H)

This is Nikon mount version.

Later renamed MC Arsat-N 50/2