[mr48chev]

You shouldn't need relays on park or turn lights.

The reason for relays on Headlights is that a lot of us use Halogen lights that draw more amps and a number of us use high powered Halogen lights that draw even more power than just the Bright 7 inch Sylvania from the parts house. I ran 55/100 watt bulbs in my 71 GMC that draw a lot of amps and before I put in the relays ate dimmer switches with abandon.
Turn signals don't draw many amps as a norm and tail and park lights don't draw many amps.

You might need relays on the tail/park lights if you light the truck up like these bull haulers who deliver cattle to Agra Beef here in town do though they look like Christmas trees rolling past the house at night.