You can buy a PlugnPlay LS swap wiring harness or you can make a DIY LS swap harness. Pat walks through what PlugnPlay harnesses do that makes them so popular. For one, every wire is clearly labeled to show where each plug & injector goes. Additionally, each of our wiring harness kits include detailed instructions and clearly labeled fuses. You can save a LOT of time going with a labeled, premade wiring harness.

Speedway GM Engine Wiring Harness, 199902 LS1
(91099021)
http://bit.ly/2ekEXIu

Speedway 20042008 Vortec V8 Wiring Harness, Extended
(91004084)
http://bit.ly/2eDexgj