My 94 started having this same problem with not starting. The difference i have compared to the OP is i started having this problem after i rebuild the starter with new factory contacts, and after installing a brand new factory fuse able link.
So i removed the starter to check and make sure that i didn't make a mistake when installing the new contacts and plunger. Everything was installed correctly, so i reinstalled the starter.
Next i checked over the new fuse able link, everything checked out. Next i checked all the ground connections to make sure they were all clean and tight, everything was clean and tight.
Problem is, the truck still doesn't start sometimes, no click, no nothing when you turn the key. Before anyone asks, the battery cables and terminals are clean and tight, and i load tested the battery and it checked out as good.
Just a question, but i seem to remember reading about corrosion inside the neutral safety mounted on the transmission can cause starting problems. So what do you think, should i pull the neutral safety switch and see if this could be the cause of my problem?