The shaft in the these turnigy motors comes out of the end where the motor bolts down / wires come out of. If is left this way and the motors are bolted back to back, as on a y6, you would need to have them spaced apart so that the shaft ends don't meet. As the shafts are about 12mm or 1/2" long, the motors would end up 1" or 25mm apart ... no good. Looking at the hobbyking site, http://www.hobbyking.com/hobbyking/s...ies_Shaft.html
, the replacement shaft does NOT have a second groove at the end of the shaft for the little clip or a second flat on the shaft for a grub screw. For this reason i think I will run with the KDA20-22L See this link and you can see the second groove for the clip when the shaft is turned around http://www.hobbyking.com/hobbyking/s...it_20___L.html
. The other option is simply to cut the shaft off and use the bolt-on propeller mount.
I thougth you just reverse the wires and run the motors in reverse if needed? ..... correct, that will reverse the direction of spin, but doesnt fix the shaft sticking out of the wrong end of the motor.