[amsat-bb] FT-847, uni-directional or be-directional version?

Hello, Does somebody know whether one can recognize by the serial number of the  FT-847 whether it is an old, uni-directional or a newer, bi-directional vrsion? A user here in Germany has two FT-847 with serial numbers 3M840064 and OE320084.

73s, Erich, DK1TB