Dittoes on this. If you run a 2.4 radio, its my opinion that runing a four cell or 4.8 volts is a brownout just waiting to happen and it does not matter which major brand system you have.

All my airplanes run five cell packs and I use Nimh which are great if you use packs that are around three times the capacitys that we formerly used with Nicd's and the size/weights usually come out close and some a little smaller than the Nicd's. In other words for say a sixty sized airplane that we formerly used say a 600mah Nicd I would use an 1800mah Nimh or larger. My only exception to this is just two of my airplanes that are controlline ships that I now use 2.4 systems to control throttle and in the case one that has a second servo to operate a stooge release. These airplanes are fine with four cell packs having only two small servos and will never be more than sixty feet away

Those servo plugs I pictured are the old Futaba 'G' plug and those will not plug to a modern Rx without an adapter or a plug change. Since you have the modern J plug then there is no reason not to try those servos. They are probably an older series but no reason not to give them a shot.

John