We found that the stock Dewalt pinion fits nicely on a 775 motor.
We initially designed our stinger to be powered by a 775 in dewalt XRP transmission. We simply modified the motor mounting to attach the 775, and moved the pinion. We designed a mounting assembly out of plastic to avoid any case-short issues since we were using other 775 motors on the robot.
It proved too heavy to use, at around 3 pounds for the drill trans, motor, mounting bracket, and winch shaft assembly. We later found a Milwaukee drill with stock 550-sized motor, which required us to only change the pinion on a legal motor (the mounting face pattern and shaft size were the same on the stock drill). The entire stinger assembly (motor, mounting bracket, winch, thinwall tube 4-bar and stinger with wheel at the end) weighed somewhere around 4 pounds, and was by far the most weight-effective non-drivetrain mechanism on our robot.
We later found a Bosch drill that required the same modifications and was even lighter. We had the Milwaukee on the robot at ship, and left it through the season, but helped team 2834 modify two Bosch drills for a bridge mechanism they build during the competition season, since we had better tooling to swap the pinions.
<EDIT>
IKE posted a paper about the two drills here </EDIT>
We also did a 'normal' CIM modification (shifter and all) for our 2010 robot's arm. We taped a 15t or so (it was +-1t of 15t) 20dp pinion for the 1/2" thread of the Dewalt, and inserted the dewalt into an AndyMark toughbox. We bolted a large split shaft collar to the AM toughbox motor mount plate. You can see it in
this picture. The pic dosen't include the shifter, we added it later. We then ran one of the sprockets (I can't remember if we used the 9 or 12 tooth) to a large VEXpro sprocket (72t?) on the arm.