So I was driving around this morning and headed over to NAPA. I was in a while, then went back out to the truck to leave. Turn the key to on, I had glow plugs and lights, then cranked it over, and I think I got 1/2 a second of cranking and everything died. No lights, no sound, no nothing. Like the batteries were disconnected. So I pulled my fuses and the #18 Maxi was blown (trailer battery charging according to the manual). Changed it and had the same problem. Pulled my battery connections and cleaned them. Same thing. Figured the starter might be loose and not making a good ground to the block, so I tightened up the bolts. Same thing. Let it sit a minute, put it in Neutral, turned the key on and jumped the starter solenoid. Same thing. Thought I might have a dying alternator leading to dead batteries which sort of "come back" after sitting a minute, so I load tested the battery. Pass. Side tested good, driver side tested good/recharge (12.3 volts, probably due to the fact that I had the key on the whole time). Got in, and it cranked right up. Hasn't happened the past 2 starts. Any ideas?