1956 Original sales invoice - How to acquire ?

Good day, been following the forum. Interesting and appreciate the good natured discussion(s).
Apologies if this has been covered - I actually offhand don't see a search - could I be pointed
in to the direction necessary to get the original sales invoice for my 1956 ?
Thanks in advance
I'm told they rescued them back in the 70's when Ford was about to throw them out. They have stored them for a long time. I received a copy, not an original so I presume the copy them as they send the original for the next guy. Good planning.