Arrma 4x4 Metal Differential Outdrives.  
Fits: 
BIGROCK BLX 4X4 #ARA102723 #AR102711 
GRANITE MEGA 4X4 #ARA102714T1 #ARA102714T2 #AR102665 #AR102676 
GRANITE BLX 4X4 #ARA102720T1 #ARA102720T2 #AR102666 
KRATON BLX 4X4 #ARA102690 
OUTCAST BLX 4X4 #ARA102692 
SENTON MEGA 4X4 #ARA102715T1 #ARA102715T2 #AR102667 #AR102678 
SENTON BLX 4X4 #ARA102721T1 #ARA102721T2 #AR102668 
TYPHON MEGA 4X4 #ARA102694 
TYPHON BLX 4X4 #ARA102722 #AR102696