No they are not. Most are simply stamped model 39A on the barrel. I have an original 1957 39M, and that's the way it's marked.
Marlin 39M's are identified by their straight grip stocks. Some were made with 24" barrels, but most were 20" barrels.
I have one marked "Original Golden 39A" mfg. in 1980 and the other marked "Marlin Golden 39A" mfg. in 1967. The difference that I can tell is the Original Golden has polished woodwork and a gold bead and trigger. The other one has a satin or oiled finish and no gold. Everything else is the same as far as I can tell.