In the large wire bundle (black plastic conduit) that is going to the fuse/relay center at the aft, port side of the engine compartment... look for a 16-ish gauge, red wire with a black, female spade connector. It might already be "poking out" of the conduit. That's the wire you're looking for. Just apply +12V to it.
1998 K2500 Suburban 6.5L TD 3.73 rear, Ron Schoolcraft 18:1, Kennedy ECM & IC, Timing gears, Splayed main caps, 3.5" Kennedy Exhuast/No Cat, K&N Filter, Boost/Tranny Temp/EGT(Pre Turbo), Ceramic-coated Manifolds, 195 Stat's, 265/75's (VSSB Adjusted) 7,000lbs (on a scale) Remote Mount Oil Filter, Remote Oil Pressure Sensor