They are basically like Taco Bell tacos, except...
The shells are made from flour tacos, so they don't crack and crumble like the brittle corn shells at TB. They are griddle-cooked, and a treat in themselves. My filling was pork, and it was a spicy pork, a red chile kind of spicy, like al pastor except more meat-textured. A fair amount of filling, maybe three or four tablespoons of meat in each taco. A lot of shredded lettuce and chopped tomato, and all topped with crumbly white queso. Two made enough for a quick lunch. $1.50 each.
What else I've liked here has been the tacos de cabeza. The meat is moist and somehow oily without being greasy. ?^) Very standard presentation with chopped white onion, cilantro, and a splash of coarse green salsa. Really my favorite taco. $1 each.
This truck is parked for most of the day at Isabel and Vineyard in Livermore, not far from Ruby Hill.