Thanks to all for your help.
I am in the process of doing a repaint on one of my U boats and thought I was missing a part when I was disassembling it.
I was thinking that there should be a spring on the rear truck bolster pin due to the cup washer being on there. I don't see a spring in the diagram, so it looks like I am not missing any parts.
Does anyone have a good source that is your go to source for Lionel MPC parts? OEM or reproduction is okay.