Since I've moved to Alameda, I've spent a fair amount of time checking out the taco trucks on International. The recommendations on this board have been great (special thanks to Ruth and Melanie)
Here are my current favorites:
-The chorizo and egg "breakfast burrito" at Ojo de Agua. I'm not a big al pastor fan, but my buddy said the al pastor burrito was great.
-The carnitas tacos at Gordo #2 (on international near 41st). I really like the tacos at Gordo.
-I had a great carne asada torta at the Guadalahara truck (outside of Guadalahara restaurant on Fruitvale at 12th street). This truck also sells chicharrones (pork rinds) for a buck a bag. Bet you can't eat just one.
-The pescado frito (fried fish) at Guadalahara restaurant is excellent. It is a whole fried fish, very well seasoned, and cut so that it's easy to pull the meat off in chunks. I didn't like the garlic fried fish (it was a bit soggy); haven't tried the diabla fish yet.