Brand new drive gear is released in conjunction with TA05-IFS R Chassis Kit and will used as a spare gear because of its drive train (37T-18T-37T pulleys). It can also be used with TA05 series drive train (36T- 16T-36T pulleys) if improvements indicated in TA05-IFS R guide are followed and if ITEM 53988 Ball Differential Pulley (37T) and either ITEM 53989 Center Pulley (18T) or ITEM 54050 TA05-IFS R 18T Center One-Way are installed.