I also use a 6v. Optima. But even better, I keep an "intelligent" trickle charger connected if I'm not driving the truck. It will not overcharge the battery.
Beware that if you completely discharge an Optima battery, your battery charger will not charge it. You have to connect the Optima in parallel with another 6 v battery for an hour or two until it begins to take a charge. Then you can put the charger on it.
Kurt
