Starts about 75% of the time but now it's not getting signal at the starter. Relay? Ignition switch?
Start with a wiring diagram .
Start simple. Take a hard look at all of the battery connections; both at the origin and terminus.
Miles on truck?
Miles on starter?
It could well be ready to be replaced. If original, it's 20 years old.
In stock, IIRC, aout $150 shipped but I'll have to look when I get home this evening.
I assume that's what he was talking about when he said no signal at starter . I was thinking he's done that test and came up with no battery voltage when key in crank position . .
Disconnect the smaller of the two wires, connect circuit tester, turn key to on, does the light illuminate?