Some years ago, my son who drives a 1984 with 4.9L [at Army base] called and said that with the hood up, where he could see the solenoid, when trying to crank the engine, there was a wisp of smoke.

The nut securing the cable which goes to the starter [solenoid post towards nearest the firewall] was loose. He simply snugged the nut and immediately, the problem was gone. After that, he loosened the cable and cleaned the post with a wire brush, applied some dielectric grease and reattached the cable. No more problems.

swmr1, your truck is almost 32 years old, so all wires and connections are suspect. Take each cable [positive & negative] off, one at a time and clean each end plus where they connect [engine block, terminal, etc..] Apply dielectric grease and reattach. Leave the ground to battery [negative] cable off until you are finished to prevent shorts. Clean the battery terminals, too.

If any insulation is frayed, cracked or discolored, replace. Universal replacements can be found at any parts store. Take your old one so they can be matched. On the six cylinder, the ground first goes to the frame and then to the starter [one piece]. You can replace this with 2 individual pieces.

Good luck!