If this is the place I think it is, its great!
We left Vegas on our way to the Valley of Fire, with our "tour guide" my brother who has lived in Vegas for 3o years when he asks if we want tacos. The truck is on the right (coming from Vegas) next to the landfill. Just before the landfill on the right if your lucky and its daytime you will see a vehicle that makes the most amazing tacos. I didn't try the burritos but the chicken tacos are great. they are small so order a few., The bulk of their business are truck drivers who like the food so much they call ahead!!
so if you see a truck parked there with a picnic table outside, you are in luck. Get the chicken ones, you wont' be disappointed!!