Ok ive noticed that if Im runnin along steady speed on highway, 65 or so for extended periods (noticed today cause had nice long drive to jobsite) that my voltmeter or ampmeter or whatever the stock dash gauge is called, would start falling over to low side (has an 8 13(12maybe) and 18 on the gauge, and it would fall to just above yellow area. However, if i adjusted speed, faster or slower it would go back up to normal, sometimes it would just pop back up on its own. Idling in traffic and all it was fine. What gives? ALternator going bad (rebuilt around a yr ago), bad gauge, what?