What revolver can it be similar to 1907 Colt Police positive But only stamped with SN on grip bottom and 39 on several places?

That COULD be just about anything- however- at one time, numerous small makers in Spain, Italy and Belgium produced copies of popular American firearms. Quality ranged from poor to pretty good. The key identifier for one of those countries would be a proofmark from that country. These were very small symbols stamped into the weapon, showing that it had been examined and tested at the government proofhouse, and found safe to fire. If you do an image search for firearm proofmarks, there are several collections that show those marks. Expect to need a magnifier and a good light to make them out. Good luck!