Must be something different then.
My truck's been doing the "surprise! I'm not cranking for you today!"
Batteries are good (12.7V) and lights are bright, etc.
Starter relay is Ok. I bypassed the clutch safety switch.
Starter is.....OK I guess....
Not original but it's a Denso I put new larger contacts in a while back.
Pulled it anyway, bench tested it, ran fine. Swapped it with a KNOWN good one (another Denso I rebuilt) anyway.
Same result. ??????????????????
I sprayed contact cleaner into the ignition key switch and it SEEMS to have fixed it.
jm.02
1998 12v 5 speed 4x4 8' bed......one of the last 12 valves 150 something thousand miles. Original owner