There are not many 40 size model aircraft that require anything more than a basic, standard size servo. I originally bought Airtronics and have collected quite a few Airtronics servos, their basic servo that comes with most of their transmitters. I've used them over and over again in different aircraft with not a problem at all.

In fact, I had basic servos in my Tiger 60 and encountered a problem with the elevator fading out during some maneuvers. This turned out not to be the servo, but the linkage flexing under pressure. I fixed that and flew that plane and flew it and flew it. It is now about, oh, 6 or 7 years old and still flys with the original servos installed.

Choose what you feel good about.. ball bearing or bushing, standard (more than adequate) or high-torque (a tad bit overbored) whatever. But, the advice given above by opjose regarding the real possibility of limited life for this aircraft, you may choose standard servos.

If you want fast response, most of these servos will work just fine with 6 volt battery packs. You will get more torque and faster response, but shorter battery life (so use a higher capacity battery pack).

Just a thought.

CGr.