The k11 bell housing code is called FB40. This pattern fits k11, GA16DE (N14/N15). I thought that the K10 was different, but I'm not certain.
But the RS5F31V code is just the code for the guts inside the gearbox. So its a 31 series gearbox (which is stronger than the k11s standard 30 series box, V means it has a viscous LSD, and its a 5 speed manual for front wheel drive etc), but the bell housing code from the k10 is what you are after to know if it will fit the k11. If its FB40, then it will.