Can you do it, yes. I have installed E-series switches on 2AA bodies a few times...but...you have to cut off the existing AA maglite internally threaded area so there will be enough wall thickness to thread. You will lose length in the body. If you wanted a 2AA light, you would have to start with a 3AA model. If you are using different batteries, maybe no problem. Also, the O-ring groove is tricky. If you cut it as deep as it should be, you will almost cut through the wall of the tube. If you cut it shallow the switch will be hard to twist. If you don't need water resistance, no problem.