Thanks Rich. Now that you mention those, I have 2 of them on deck that I never got to 2 railing! So the SD50 was the closest. It must have a hair more room as it works.
You can see by your work that the MTH truck is a cast piece so the only thing I can think of easier, would be to cut a small area off the tab with a radius to create the room. I don't know what engine Dave spoke of that would have that tab removable?
Can you machine off some of the mounting blocks on the stock pilots? I had a MTH engine like that and I remember grinding something to raise the coupler??
If the body is low you could shim it slightly to help?
Edit: I have another BN SD45 that I did convert. I used the KD 843 short box. The difference maybe that I made my own shims and mounted the couplers to the original pilots. So I could adjust the height and how far the box sticks out on mine. It just fits and rubs a bit when handled off of the track in the front only.
It's getting bad around here? I don't know what I did!