Heavy Duty The HS-645MG Analog Rudder Servo is one of our favorite servos of all time.
Standard Size by Hitec RCD Inc.

Overview
The HS-645MG is one of our favorite servos of all time. Metal gears, dual ball bearings, seperated motor and circuit board make the HS-645MG a top choice. 

FEATURES:
Control System: +Pulse Width Control 1500usec Neutral
Required Pulse: 3-5 Volt Peak to Peak Square Wave
Operating Voltage: 4.8-6.0 Volts
Operating Temperature Range: -20 to +60 Degree C
Operating Speed (4.8V): 0.24sec/60° at no load
Operating Speed (6.0V): 0.20sec/60° at no load
Stall Torque (4.8V): 106.93 oz/in. (7.7kg.cm)
Stall Torque (6.0V): 133.31 oz/in. (9.6kg.cm)
Operating Angle: 45 Deg. one side pulse traveling 400usec
360 Modifiable: Yes
Direction: Clockwise/Pulse Traveling 1500 to 1900usec
Current Drain (4.8V): 8.8mA/idle and 350mA no load operating
Current Drain (6.0V): 9.1mA/idle and 450mA no load operating
Dead Band Width: 8usec
Motor Type: 3 Pole Ferrite
Potentiometer Drive: Indirect Drive
Bearing Type: Dual Ball Bearing
Gear Type: 3 Metal Gears and 1 Resin Metal Gear
Connector Wire Length: 11.81" (300mm)
Dimensions: 1.59" x 0.77"x 1.48" (40.6 x 19.8 x 37.8mm)
Weight: 1.94oz. (55.2g)