I managed to find out that the large one has center-tapped coils. I also found out that Coil 1 is red-white-brown, coil 2 is blue-black-yellow. I found the schematic below on http://ashishrd.blogspot.com/2007/09/computer-controlled-stepper-motor.html
I was wondering how this could be adapted to control my motor from a PC program with the ULN2003 (that chip sounds like UT2003)?
Here are the complete residences of what I found on the wires with a multimeter, in case that helps.
Red to Brown: 8 ohms (or 7 some times)
Red to White: 4 ohms
White to Brown: 4
Blue to Yellow: 7
Yellow to Black: 4
Black to Blue: 4