Central Locomotive Works made a kit that used their Alco side frames. They show up occasionally at train shows and auction but it's really hit and miss. I have two of those and they run well, but they do have the Alco trucks. Not really practical to use flywheels on the motors, too little room.
I have modifed one using a Weaver drive (the P&D is basically the same if you get one without sideframes). You have to figure a way to use the Rivarossi side frames off the trucks. They are plastic not delrin like the Weavers were so you really need a bearing or it is going to wear out. I have tried a lot of different things, currently I am using 3/32 brass tube as a bearing surface.
I did another one with Mashima motors replacing the Rivarossi motors. I powered both trucks. That works OK and was the easiest of the modifications. I plan to sell that one as it doesn't match the others.
Finally, what I am using now and I really like is the I use an All Nation drive with Lionel FM truck side frames. I made a drill template out of styrene and put NWSL brass bearings in the trucks. You could also drill a slightly larger hole and use the ball bearings that the RC car folks use. I made the truck bolsters from styrene and used all wheel pick up.
I've posted some of this on the forum, it never attracted too much interest. I expect there are others who have more experience than me.
Feel free to contact me (my email is in my profile) if you have questions. Good luck!
