Arm vs. Drum - sorta
I am using a Hitec HS-815. It has 275 to 343 ounces of torque (depending on cell count), and 140 degrees of throw. It uses a Y connector on the servo lead. The battery plugs into one fork in the Y and the servo goes into the other, and the "bottom" of the Y goes into the receiver's controlling slot. (I use channel 3.)
I actually had to limit the throw using the end point adjustment on my radio. (I think I could also put in new holes closer in on the arm, but the EPA works well.)