Whenever I'm on a job, I'm always looking for an outlet or an extension cord. So I decided to replace the 6 foot cord that came with my drill, and put in a 25 foot cord.
I want to give a special thanks to Instructables Hall of Famer Phil B. Phil provided me with the advice I needed to do this properly. Be sure to check out his Instructables page.

Step 1: Remove Old Cord

Open your drill case and take note of the wiring so you can rewire the drill properly. Its best to take a picture so you cant forget it. Be careful to put your screws away as you take them out so you dont lose them.

Step 2: Prepare the New Cord

I found this spare cord on a job site, it was headed for the trash because it was missing the female end. You can use any extension cord and cut off the female end. Inspect the cord to make sure its not damaged. Cut and strip the insulation from new wires and twist the ends.

Step 3: Put It Back Together

Now put it all back the way it was with the original cord. slip the cord protector on before you put the wires in place. The original cord only had a black and white wire. my new cord had a ground wire (the green one) also but I just cut short and left it unconnected. Put the other side of the frame back on. Don't overtighten the screws.