Disassembled the car. Seemed to track well with nothing rubbing or hanging up on slightly tighter than minimum 072 curves.
Parts list.
Atlas universal truck mount. Not really sure what this actually fits. It at one time came with their replacement trucks.
A washer that fits snuggly over it.
A washer. It is dished shaped with a rubber washer adhered to the flat side. Intermountain used these to mount Weaver trucks with 3 rail couplers in order to gain clearance on their tank cars. Not sure what they are called. I did see them at a local hardware store once in with the nut and bolt bins.
2 56 x 1/2 threaded screw and 2 washers.
Enlarged the rubber slightly so that it fit over the Atlas bushing. I drilled through the Atlas bushing and threaded the 2 56 screw into it. It's pretty much a slip fit except for the headed portion you drill with a #50 bit. The truck mount screw will grab enough to mount the truck securely. You can opt for a longer screw and nut setup as there seems to be enough room.
The Atlas bushing fits loosely in the MTH frame. The washer seems to keep it centered as you tighten up the truck mount screw. The dished metal washer should somewhat force it's way on to the Atlas bushing. A little bit of Walthers goo before assembly and it should keep everything permantly centered. Just tightening up the truck then backing it off a bit seems to keep it dead centered though. The 2 small washers were used just to raise the car slightly and get the coupler the right height.
As mentioned I used Kadee's offset couplers. Dave, I read your post. I see how you were able to use the stock Kadee's. I went for the more less evasive approach. In case this didn't work out.
I'm pleased with how the car looks. Huge improvement. Is it feasible to do. Probably not if your doing a few. Don't know where you could obtain the Atlas mounts. Lionel will probably do a version of Weaver's trucks. You need to purchase trucks and really not sure if there's a market in reselling the MTH trucks to offset the cost. I may look for a junker and try Dave's method. Still dread hacking away at the MTH trucks. The Weavers just made it so much easier.