That is a chassis broadcast sheet, there is also a body broadcast sheet. that sheet will have specifics to the chassis only. the body sheet will have more info on the interior. not sure how you could open that up, might try a document restoration specialist they may have chemicals that might help to allow the paper to soften without destroying the original printing. good luck, very cool to see that it was found.

I would also say to use a company or a university that specializes in document preservation....Joe