thought i would update this old thread,the gear reduction units are still working,but i only drive the tank about an hour a week.just recently i added a set of impact tracks ,so we'll see how long they last.i thought these were reduced 2:1 but after watching some tanks with a 3:1 gru i believe they are closer to a 4:1 gru.they slowed my kt way,way down,to me it looks slower than than a 3:1 gru.i may change the 10 tooth pinions to 12 tooth and see if that makes it look more scale,well it does'nt really matter becuase i have only 40$ tied up in the gear reduction.if they fail then i'll start looking for a set of 3:1 tu's.