Could it be a Mega Motors ACn Car8?
If so it is:-
40mm square by 72mm long
372g
1270kv
recommended to use 4-5s
Hot Bodies Lightning 2 Pro carbon, Mega 22/30/2, MMM, 4s3-5Ah.
Tamiya F201 carbon, Mamba 7700, MM, 2s A123 2.3ah.
Xray XT8, 1518, MMM, 4s5Ah.
Lots of boats.
fastelectrics.net