the way you describle them it is the older barrel ones. but i dont see how this would effect it, as it goes flat chatt off the ground and spins normal but as soon as hits the ground power dropps. as soon as it comes againts the smallist obstacle in shutters, and even with the diff tight if i hand spin the wheels (rear) they both go different directions. should this be happening with a tightish diff, could the diff be the reason for me loosing all of my power as soon as the motor comes under load.