1995 379 peterbilt Head light switch how to wire IT with relays

I'm not sure if this is a question or not, but it would be no different than other relays. Most relays have the schematic on them, follow that. If you are asking which wires are which on the headlight switch, do a search, the schematic for your truck has been posted many times.

You might get some better answers with more information, like what exactly are you trying to achieve with these relays?

 

I thought a 1995 379 already had relays for the headlights?

 

Not sure about the 1995 but '94 and before they only had relays for switching between highs and lows.

My 1989 doesn't even have the relays for clearance and marker lights. Those weren't added till 1991.