Umm, I think that the Tin Fork columnist for the SD Reader (sorry, I'm blanking on his name) recently wrote about a good taco truck there that serves the commuters.
Have not been their in about 6 months. This was my first Experience with Mariscos German (3 Years ago). Thier first truck started hear at Truck 1 3269 Beyer San Ysidro. Its still their. Out of all the locations I always seem to get the largest portions their for some reason. Check out my Gobernador from that location.
Their is a few more places I used to go to but the locations skip me. I will circle back if I remember