Dave, Yes, it should have a thrust washer and technically that's a postwar brush plate, the prewar ones don't use the tubes like that one. Also, take a look at the frame, one of the ears that the field winding sits on is slightly bent. If you try to straighten it just be real careful. If it breaks we'll have to find another frame.
I guess the other thing we could try would be to put the prewar wheels on a postwar S frame with the smoke unit and maybe you could have smoke in that 556. The only difference in the wiring between the prewar 556 and the postwar 350 is that the postwar field has both ends of the winding as wires going to the e unit and the prewar 556 has one side going to the ground on the chassis since it is three rail. I have E unit fingers if it needs some, but you can get those from Henning or Jeff Kane. I also have the rivets for holding the trucks to the tender and car frames so you can remove those to do your painting. If needed I'll take one of mine apart and make up a wiring diagram for you. You should be able to straighten that bend in the pilot as well, just be gentle or you will need to get out the JB weld to fix it.
One other comment, They do make a con motor conversion for these (well for the S scale ones) and that is an option too. I think some of the guys on the S scale forum could provide some info if you wanted to go that route. I'll dig deeper and see if I can find some lead and trail trucks for you. I also found a 1615 switcher front coupler bracket with the coupler for your other project, the 0-6-0 switcher. It was bent up a bit, but I think you could straighten it and reuse if you want. We can figure out what you'll need that I didn't get in that first box and I'll send you another one