I know this is an oldie and is still getting posts. I don't have a good comment on the above post (LMC) way. It depends what truck you have like 69-72 Fleetside/Blazer separate numbers form 69-72 Stepside also separate numbers also for the 67-72 Panel and Suburban they use two sets separate numbers. Three different numbers for three different styles of trucks.
Brothers sells the brand M&H for Wiring Harnesses.