with all the replacement wiring harnesses out there now a days. Does anyone make them for the 73-79 ford f-series? if so can the factory gauges be used?

 

Your going to have to find someone who specializes in the older F-series. Most of them I've seen are for classic Mustang, Camaro, Nova, ect. Try contacting a few of them, Dakota Digital used to do some one off harnesses, TPI wiring and possibly even Painless Wiring.