[4ofakind]

Chris Google battery isolator.

You need a 4 post battery isolator rated @ 200 amps. A battery isolator is just as the name says. No two polarities on a battery are equal and if you connected them directly together the difference will cause them to drain each other when your truck is not running. The isolator keeps the batteries seperated when your truck is not running. When your truck is running and your alternator is spinning it connects the two batteries so they can charge together. A 200 amp isolator will allow up to 200 amps to flow to the two batteries so you have headroom for your 160 amp alt.
Two posts are for the positive posts of each batt. One to one batt. The other to the other batt. One post is for the ground connection. Don't connect it to the neg posts of the batts. Connect it to a ground point on the truck. The last post is for your ignition switch so the batteries are charged when the truck is on and seperated when the truck is off.

Mal