I don't know how I missed your original thread, but I recently had the same thing happen. It was weird because sometimes it would work and sometimes... nothing. I figured the starter was toast (dead spot?) and then I took a better look at what looked like a tight starter cable connection to the battery. Turns out I could gently rotate the ring terminal by hand - it wasn't loose enough to be able to "rock" the ring terminal, just enough to rotate it. Tightened it up and all has been good.
Glad you got it figured out!
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