OK, so I did it your way with this F3 Dummy B unit. I used lock washers like you suggested, but double them up because I didn't have the same thickness as what you used. It dropped it a little bit more, and that's about as far as I can go with out clearance issues.
Also frame mounted the steps that were removed from the trucks. Actually it's a different step, but looks much better. The buffer plate under the diaphragm needs some modification as it won't allow the unit's to turn because those buffers are rigid. I'll either cut them back shorter, or remove them all together.
If you look at the buffer under the diaphragm, you can see how much lower it is, and the gap caused by the truck mounted step is gone as well.
