This HV50P servo is ideal for 1/12 LMP and GT12 racing. 
Tiny in size and weight but mighty in its performance the HV50P has been developed by European Champion Max Machler for pan car racing. 
Black RX lead and a 25T Spline 
 
  Torque (3.7V)?3.75 kg-cm / 52.08 oz-in
  Torque (6.0V)?6.1 kg-cm / 84.71 oz-in
  Torque (7.4V)?7.5 kg-cm / 104.16 oz-in
  Torque (8.2V)?8.3 kg-cm / 115.27 oz-in
  Speed?0.157 s (3.7V)  /  0.097 s (6.0V)  /  0.079 s (7.4V)  /  0.071 s (8.2V)
  Weight?18.1 g  (0.64 oz)
Dimension?27 x 12.1 x 27.7 mm
 
Options to help mounting the servo 
ZENP005
or
U7680