The "B11" has nothing to do with Stall. it pertains to Chinese MAVN E. I.e., a circled B# of 11.
E. The MA and all MG have B11. This is signified by “B11” in red on the counter (bold in the Vehicle Listing). If “B(11)+” appears on the reverse side of the counter, the MA’s B# is a circled “11” (D3.71) for scenarios set in/after 1941 (non-circled B11 remains applicable to the vehicle’s MG in such scenarios).