DC tac hook up..?..

Well I just called autometer and basically they said I had a paperweight..
Or so they didn't want to touch it because it was an original Chrysler item and altering it sounds like they could get in trouble... He said something about a generator distributor?... He also said it had a very primitive circuit board inside. I asked about altering the circuit board but they said they couldn't touch it and if I wanted to do something like that I was on my own.. maybe when I get time in the next couple weeks I'll dissect it and figure out what I can do.. maybe put the guts of a normal tachometer inside of it...