Jack - I am sorry if I was unclear before, so I am going to explain myself more clearly.(I am going to start at the beginning)
There are 2 kinds of battery cables - 2 piece and one piece. The one piece has the lead(element-Pb) molded permanently to the copper cable. the other has a lead(Pb) terminal clamped to the cable. Is this like the end of your battery cables?
Picture If so, you need to remove the 2 bolts on the top, and clean the cable end(copper), clean the corrosion from the lead(Pb) inside the the
battery terminals, and the plate(oval washer with 2 holes in it) It is best to use a wire brush to do the cleaning on the lead(Pb). Also be sure the plate is flat when you re-connect it to the battery terminal(My father used to just flip them over). You can have this area clean and tight, but if the plate is bowed - it might not squeeze the cable tightly enough. This is what I meant by "either between the battery post and terminals, or between your battery cables and your terminals" earlier. The post is the lead(Pb) positive and negative on the battery.(not the copper stud on the starter) The terminal is the connection between the copper cable and the battery post. If cleaning the terminals does not work, sandwich a
star washer between the negative cable and frame, one between the ground strap and frame, and one between the ground strap and engine.(I am thinking that the ground side is not your problem though - I included this part to be thorough for all who may read this in the future)
If your battery cable is the
one piece type, it will likely need to be replaced.
Try a jumper cable on the positive half of the circuit only. If the truck starts - the positive side of the circuit is the problem.
