I'm not familiar with SBT's at all, being that I collect doubles only.IF it is a Specialty, however, it is the only one that Marlin made(1948)!
Researching your S/N further, it falls in the 1947 production, so, likely it is not a Specialty. I suggest you go to the home page, select post-'13 guns and compare your engraving to the illustrations shown to determine the grade. Also, look on the watertable for a letter above or below the serial number sequence. On doubles that letter denotes the grade--ex-I= Ideal, T= Trap, C=Crown, etc.
Short answer to your question---- I don't know!
If you have pics of the side of the receiver send them to me via the "envelope" next to my name above.