Thats correct its a different bearing to the later engines.
Try and get the Axe p/n as its a high speed bearing.
I matched up bearings before but they didnt hold up as well as the Axe one.
casterracing EX-1 Pro, SP Silver Arrow
TOP Racing Scythe, SP 17.5, SP GT Pro 2.0
TOP Racing Scythe, SP 4.5 V2, Hobbywing Xerun 120SD 2.0
TOP Racing Scythe, SP 13.5, Hobbywing Xerun 120SD 2.0