Interesting subject.
First off, I'm always interested in "how" to restore a part/component rather than immediately ask "where" do I send it. I'm always interested in learning how to restore/rebuild a part myself. Most of them aren't that complicated, but when I do have to send something out I have before pics.
That being said, when I start a restoration, I take clear, high-resolution pics of every pn or date code I find before any work is started. I also try to take pics of the part while in the process of resto, as well as once its finished. The same goes for any paint dabs or markings.
The stampings, tags, etc. are so scrutinized these days (and for good reason), so I send all pics/info I have over to CRG (Kurt can attest to that, Im sure
) because they keep such a well organized db. I think of it as good insurance for if/when something may come into question in the future.