Hes not asking for an ESC or a combo, hes only asking for a motor. There is no 1/10 scale motor that I am aware of thats going to power a 1/10 scale RC and pull a 15.4lb load. Even if you managed to find one that would do that without overheating its going to be geared so low that its going to...
you're not going to be able to tow a 7KG load and also go fast. You can haul a 7KG load and then change pinions and go fast without the load though. Would help to know the scale as Tunedpipe mentioned. You can look around at TPPowerusa.com. You should be able to find some big motors there.