WE had no problems with the drill transmissions and have used them in combination with the chips in two different transmissions (a 2 speed and a single speed). They are fairly easy to mount and we ran them in high gear. Although we used the drill transmissions and the mounts provided, I do not like the mounts. They are flimsy and you have to be careful not to overtighten and warp them. Everyone should take apart the drill transmissions at least once just for fun
. The thing to be careful with when you are using the drill transmissions is to make sure that the transmission and the drill motor are securely held together and that you use enough zip-ties to lock it in gear properly.
-Aaron