I recently got my hands on the Service Manual for the 2019 Mac Pro. The 2010-2012 Service Manual was incredibly helpful, and nobody else seems to be hosting this, so I figured I might as well contribute to the community a bit.
Too large to attach as a file, so here is a media fire link.
2019 Mac Pro Service Manual
Source: https://forums.macrumors.com/threads/2019-mac-pro-service-technician-manual.2329772/