The power trucks came from GHB International in Maryland, they are $160 shipped...You get two indentical trucks and a working metal pole with tie down hook. The trucks have a DC motor and lots of brass gears. The third rail pick up is a button instead of a roller so they have a nice low profile and the scale wheels don't hurt either. The trucks are a drop in replacement for the dummy trucks. As far as removing the body goes, it is only needed if you want to install the pole. I did. You will see 4 metal poles in the body, the floor is installed by a press fit into these poles. The only way to access the inside is to ascertain the postion of the poles with relation to the floor and use a 3/16 or a size smaller drill bit to drill out the mounting points, two of which are under the front truck, you can get the floor off by getting the rear part off first, it is held in place by a small metal post and then disengaging the front from the nose of the body. After the body is off you can install the pole, pretty straight forward, comes with good instructions. I super glued a brass tube slightly bigger over the inside metal pole, #3 from the front...While it set up I assembled the copper strips and installed the motors, both of which are identical so you have all wheel pick up and two axles powered, one on each truck. Oil and grease the gears and give it a test ride.
Now you are ready to put the floor back in. The brass tube I threaded for a 2:56 screw. You only need to use one. With the floor being a tight fit and held in place be the rear and the front, you may not need the screw. I know this sounds rather lengthy but the actual time was about 1.5 hours for complete conversion. Using a Lionel transformer is not the best control because of the usual 5-6v on point. The start speed at the minimum is slightly high, I think a better way to lower the starting speed might be to go with a rheostat, were you would have a 1-5v control and higher...
Marty