Alright so I'll try and be brief. Weather started getting cold and truck began cranking slowly and went to leave work I got a click. Starter is a year old and the battery is about 20 months old, I had both tested at Advanced Auto and they test just fine. I replaced the sidemount solenoid and both battery cables and the solenoid to starter cable. After I replaced the cables the truck reluctantly started up and then clicked again the next time I started.

I'm out of ideas on this one so any help would be great. Does the battery just not produce enough power to start the aging truck? The wiring was jerry rigged a bit when I inherited the truck but just to clarify the pos cable goes into the sidemount solenoid, solenoid to the starter. The Neg battery cable is grounded on the starter as well.

 

bad ground to the frame possibly? does it have a block heater? if so, try plugging it in. The clicking sounds like a dead battery to me, but if you say it's new that could be out. Has the solenoid been replaced? Starter may be pulling hard though.

 

It sounds like a bad ground but since your cable is new you may need to add another ground cable.
On a 96 the stock cable runs from the (-) post to a point on the frame on top of the wheel well arch and then down to the block ground at the starter flange. I assume a 94 is the same. The intermediate point is where this cable always corrodes out and the parts store replacements do not even have it.

If your cable does not have the intermediate ground point, you should consider adding a cable from the starter flange back up to the frame.

 

So in addition to the negative cable running to the starter I should run another wire from the starter to the frame? I have a length of 12ga wire and some eyelets I could use or should a run another 4ga cable? Could I unbolt the solenoid and mount it behind that?

 

12 ga is WAY too small, never go under 6 for a ground cable and bigger is always better.
You can get pre-made 4 ga cable with eyelets at both ends at AutoZoo or Advance.

 

So I mounted a second 4ga pre made cable running from the second starter bolt to the frame. Stick with me here: I have the positive cable running to the side mount solenoid and the starter solenoid, the negative terminal on the battery runs as a ground bolted on the starter, another 4ga wire now runs from the the sidemount solenoid to the starter solenoid. Now in addition I have the second ground running from the other starter bolt to the frame. When I first did this configuration the truck slowly cranked to a start and I let it run for 5 minutes or so then I tried to crank it up again and it clicked on me yet again. I must be missing something here.

 

Try running a jumper between the two large posts on the solenoid, the engine should definitely crank doing that. Then try running a jumper from the positive battery cable post to the small terminal on the solenoid, the one with the slip on wire. Tell us what happens. SAFETY FIRST make sure the transmission is in park or neutral and the ignition switch off unless trying to start the vehicle.