REMOVE ALL BATTERY CABLES
1 - The truck still has two alternators so it is more than likely still a 24v setup.No indiactation that anything has been butchered
2 - You will need two batteries
3 - You will need to make a jumper wire to feed the 12v side of the truck. It hooks you at the diamond shaped 12v terminal block.
4 - You will need a battery cable between the two.
If the cables are missing you can get some from WalMart/autozone. Depending on what batteries you use I would use the marine terminal for the posts and use the thumb screws to connect the cables.
4a - remove the starter relay from under the dash and disconnect it. We don't want a runaway starter
5 - Hook up the positive terminal of the front battery and also connect the jumper wire for the 12v system
6 - Hook up the negative terminal of the front battery. Then turn the key to the "on" position. Do not start. You are checking for any indication of lights/power in the cab.
7 - disconnect the negative cable.
8 - connect the positive terminal of the front battery to the negative terminal of the rear battery
8a - connect the positive terminal of the rear battery
9 - connect the negative terminal of the front battery
10 - check for any flames or sparks
11 - very carefully reinstall the starter relay under the dash.
12 - If everything looks okay quickly bump the key to see if the starter will engage.
13 - Report your findings and any issues that arise
14 - If everything is okay then we will attemp to bleed the fuel system and start the engine