For the OLDER MILK CARS I've seen articles that have you drill out the rivets holding the truck side frames together and then re-riveting them back together. Are these articles for real? Just carefully spread the truck apart letting the Lionel wheelset fall out and then carefully insert the O scale wheelset of your choice. I use a tack puller to bend the metal flange, that holds the coupler shaft, out of the way after I remove the C retainer. To remove that tab so it doesn't interfere with the coupler/wheel swing, use aviation shears. A Dremel motor tool takes forever and makes a mess. One snip with the sheers and you are neatly done. Take a swipe with a metal file where the tab was removed and the wheel conversion is done. What really makes the conversion a snap is Gandyman & Son Trains coupler pockets found in Shapeways. Its been a while since I've done one but as I recall you unscrew the screw that's in the way of the coupler pocket, drill another hole for the second coupler pocket hole and secure the pocket with two screws. Assemble the Kadee coupler, check with the Kadee coupler gauge and you are done easily in under 15 minutes. See https://www.youtube.com/watch?v=srz8qs4JhBo for a nice how-to video for the OLDER MILK CARS. Thank you, Mario!