Faulhaber Gearmotor with right angle head and Encoder.
http://www.robotroom.com/FaulhaberGearmotor.html
http://www.goldmine-elec-products.com/prodinfo.asp?number=G16279
1524E006S123
15/5S141:1K832
HES164A

Motor Part Number
1524E006S123 not 1524E0065123 as stated in Electronic Goldmine.
15/24 = Body diameter/length mm
E = short shaft
006 = 6V or 3V to 9V
S = Silver alloy commutators
123 = special order
11 ohm winding resistance

Gearhead Part Number
15/5S141:1K832   not KB32
15             = inner diameter mm
  /5           = series
    S          = Steel gears
     141:1     = gear ratio actually 140.759183:1
          K832 = special order
The gearhead has two M2 (2 mm) screw holes.
The gearhead also has two 2-56 UNC screw holes
surrounded by a thin circle to differentiate them.
(It is thoughtful of the manufacturer to include both
metric and imperial threaded holes on the gearhead.)
The screw holes are 3 mm (0.1181") deep. 
shaft = 3mmDia x 4mm length.

Right Angle Drive Box

Encoder
HES164A
HE = Hall Effect
S = series
16 = 16mmDia
4A = special order

Similar to the HEM encoder which is:
4.5V to 15V, This works fine on 3.3V.
A & B open collector output
with internal 10K pullup to the 5V pin.
A and B could be called Clock and Data.

DIP Connector
+---+---+---+  +---+---+---+
| 6 | 4 | 2 |  | -M| B |+5V|(3.3V)
+---+---+---+  +---+---+---+
| 5 | 3 | 1 |  |GND| A | +M|
+---+---+-^-+  +---+---+-^-+

SIP Connector
+---+---+---+---+---+---+
| 6 | 5 | 4 | 3 | 2 | 1 |
+---+---+---+---+---+-^-+
                (3.3V)
+---+---+---+---+---+---+
| -M|GND| B | A |+5V| +M|
+---+---+---+---+---+-^-+

Motor Driver
(Power)             (3.3V)
+---+---+---+---+---+---+---+
|Pwr|Fwd|GND| B | A |+5V|Rev|
+---+---+---+---+---+---+-^-+