The 39 is probably for a 127mm Ektar in supermatic. I can actually go one better than the Symmar-S I havw listed. I also have an old (1950s)) convertible Symmar in Copal. Its a 210/370. At 210 it gives up little to the S and at 370 Its okay. But It's hard to argue two focal length for the price of one. As for price, $100. I can throw in a couple of DDS and might even have a spare slide for the one you have.

Dan