ive accually replaced the servo with one that came with the truck its a JR Z550 here are the specs.
Basic Information
Modulation: Analog
Torque: 4.8V:51.0 oz-in (3.67 kg-cm)
6.0V:62.0 oz-in (4.46 kg-cm)
Speed: 4.8V:0.21 sec/60°
6.0V:0.17 sec/60°
Weight: 1.47 oz (41.7 g)
Dimensions: Length:1.52 in (38.6 mm)
Width:0.73 in (18.5 mm)
Height:1.32 in (33.5 mm)
Motor Type: 3-pole
Gear Type: ? (add)
Rotation/Support: Single Bearing