I found this on the interent today on another forum and as of Jan 2005, this was still true. I copied the post so you can read it as is...
You can get an invoice thru this source. They only can recreate invoices (only Dealer Invoice) from 1978 and up car/trucks. Some 1977 data is available but most 1977 and earlier was purged from the system long time ago.
Must have the correct VIN, triple check it before sending it.
GMMA.research@gm.com 1-800-851-8984.
There is only 1 girl that does this and it may take some time for her to search for it. She has done both my cars. It will list all the options and also the original dealership to which it was sent. It also list the MSRP of the options along with the Invoice price.
Best of all......it is FREE!!!
I thought is sounded a little too good to be true, but I emailed my VIN numbers and sure enough, received a envelope from GM Media Archives in the mail a few weeks later with the invoice. I recommend it to everyone without original paperwork to verify any original or rare options.
I sent in my VIN and am waiting impatiently..