wiring 72 chevy truck

The pink is a resistance wire from your IGN sw (IG terminal) to your coil(+) side. It has to be a specified length to produce the correct resistance to lower the current to the coil. So don't cut it if it's too long. You can't splice it either. If it isn't long enough, there may be some coiled under the dash.

Don't know about the others

Re: >"three wires come from firewall

blue--- need to know what they connect to thanks"

------------------------------------------------------------ Brn/Wht goes to ign switch lso.Blu and lt.Blu go to ws wash/wipe