[68GMCCustom]

I never hooked it up......but as per my understanding of the application...yes.

This harness plugs into the coil packs and the MSD box....taking the timing over and running it thru something you can control (the 6LS) w/o being inside the pcm/ecm. And yes....leaving everything else under pcm/ecm control. If you can read the white sticker it says LS2 EFI to 6012 w/58 tooth....so its for genIV...LS2 was early genIV.

from Summit's description: These MSD 6LS Ignition harness allow you to easily connect the 6LS-2 to a factory EFI system to take advantage of timing adjustments and settings. MSD's 6LS extension harness allows you to reach the front-mounted cam sensor on an early (24-tooth trigger wheel) LS2 when installing a 6LS Ignition Controller. The 6LS-2 Controller allows you to map a timing advance curve with MSD's easy-to-use Pro-Data+ software.