Unfortunately As of Jan 2012 This kit is now discontinued from Western The DRL heat sink is not available to them so once these are gone you will be forced to use the new Isolation module wiring.
WE HAVE come up with a replacement kit at this link 63392 Replacement
Here is a new wiring set up 63394 for a 1999-2002 Chevy or GMC with HB3-HB4 headlights with the Day time Running lights For Western Unimount or Fisher Relay style wiring. This has, headlight harness 26071 Western and parts bag 64082. This kit does not include the control harness If you want that kit # 63392 is the kit you need. If you don't have the power harness you will need to add that to the cart too. Or if you only need the light harness we have them listed also. set up to run the day time running lights. Make sure this is the correct kit for your truck Only fits HB3/HB4 1999-2002 GMC All New style Sierra and Chevy Silverado. Don't forget to add a tube of Dielectric grease to protect these plugs.
Here is a link to the Wiring Instructions
Here is a link to the Parts list for this kit