This same "withholding information" scenario happened in Australian mopar circles with the Aussie Charger R/T's.
A half dozen guys had the paperwork on all the R/T's produced.
People had to beg and plead to get info on their cars. That all came to a halt when the paperwork was finally published on the internet.
Crazy thing was those half dozen guys holding the info were the main ones rebodying cars and stamping engine blocks. They made out like bandits with cars pulling up to $150k Au.
Just give the guy his damn dealership info. It's not hard.