STOCKTON - When it comes to taco trucks, my friend Kevin has his favorite.He claims that Taco San Juan, which is usually parked everyday on East Alpine Avenue and Wilson Way in Stockton, is the best.“They really know how to load up the meat (on a burrito or taco),” Kevin recently said.A carne asada burrito might run you about $4. But that includes all of fixings such as rice, beans, salsa, cilantro, and onions.When it comes to taco trucks, my choice meat on a taco is carne asada. Many mobile vendors charge $1 to $1.25 for the flat corn-tortilla tacos or “taco-truck tacos” as we call them.Where else but on a taco truck can you get lengua (tongue), cabeza (head), pollo (chicken) or carnitas (pork) on a burrito or taco.Going to your favorite taco truck might mean going into a questionable part of town.