It looks smaller than the OM and the olympus didn't have that square notch.From memory it looks like my old Olympus OM1n, I could be wrong though. Is it a Zuiko lens
I did look there and couldn't see it. The lens is a third party one, weighty and solid. I wanted to try it out on my Olympus digital but for the life of me cannot identify what adapter I need.Have you tried this...
SLR Lens Mount Identification Guide by Richard Oleson - Vintagelens
So you’ve found a lens and you don’t know what camera it fits? Scroll down this set of photos until you find the one that it looks like. I don’t have everything here, but I have most of the more common ones for manual-focus, focal plane shutter 35mm SLRs. Quick notes on lens-mount compatibility...vintagelens.nl
I realised I have an Olympus OM adapter so I tried it and it didn't fit. It's not an FD either though it almost fits my Canon A-1.From memory it looks like my old Olympus OM1n, I could be wrong though. Is it a Zuiko lens