Possible history of the BMW branded differential fluid for the E9X M3:
BMW 75w-140 Limited Slip GL-5 standard differential fluid, aka SAF-XJ (2007-2016) = Rowe Hightec Hypoid EP SAE 75W-140 S-LS (same style small cone caps for both BMW branded and Rowe branded which was also sold under the Mopar and Ford labels)
BMW 75w-140 Limited Slip GL-5 differential fluid with extra friction modifier, aka SAF-XJ+FM (2007-2016) = Castrol Syntrax SAF-XJ 75w-140 (exact same design for the cap on both of these bottles, green cap for the BMW branded oil and red cap for the Castrol branded oil)
BMW 75w-140 Limited Slip GL-5 rated differential fluid with extra friction modifier, aka SAF-XJ+FM (red cap bottle 2016+) = Shell Spirax S6 AXME 75w-140
Other OEM equivalents can be found in this link
here.