Mike's RC Monster heatsinks fit well, but, on the 80mm they stop just short of the wires which is ok.
The 70mm is shorter than RCM heatsink.
I heard that there's a little fan unit that goes onto the back of the motor to draw air through it, but, I've never seen it.
See the flat spot on the shaft?
Losi SCTE SC4 Pro 4000kv, Tekin RX8, 2S
MP7.5 Kanai III Tekno Neu 1515/2.5D 1700kv MM 4S
LST 2 Carbon CC 1717 1Y 1580kv MM 6S
Futaba 3PKS Spektrum Pro