Thanks, Pieter, again for your research work. It is interesting that such a detail - the stack or exhaust pipe - allows us the identification. It would be interesting to know why this ship had that detail - perhaps experience from former sisterships?

My second observation supports however your statement that Kaunas is the only one of the Design 563 tankers that has this stack on the funnel. (I have photos of all 63 vessels of that design). So KAUNAS it most likely is.

My first choice would be OCHAKOV, purely based in the the first carcacter of the name visible on the stern. Second choice would be the FRUNZE, where the Cyrillic F caracter resembles an O but like the Greek PHI/F caracter.