• Assemble the Hella lamps first by carefully aligning and inserting the H4 bulb in the receptacle and fastening the spring clips to hold the bulb. Firmly push the silicon dustcover over the back of the bulb. You must push down hard on this to seat it properly on the bulb. Push the Hella supplied adapter onto the H4 bulb connector.
• Now on your truck, remove the 4 screws holding the retaining ring on the OE lamp being careful not to change the aiming adjusters.
• Carefully remove the lamp from the bucket and remove the connector from back of the factory sealed beam.
• In order to install the Hella headlamp, the male connectors from the small Hella wiring adapter supplied with the lamp need to be removed from the plug. If you look on the inside of each flat male connector, you’ll see a small rectangular opening. If you slip a paper clip or small jewelers screwdriver into this opening, you can release the clip that holds the pin in the connector and slide it out the back of the connector.
• Now connect the female connectors from the OE wiring harness as follows:

Brown GM to Yellow Hella

Black GM to Brown Hella

Green GM to White Hella

• Now install the Hella lamp by reversing the procedure you used to remove the OE lamp.
• Now do the other side of the truck using the same procedure.]

For general wire sizing information, you may want to check our Sensible Wiring Guide.