I consider this to be my "secret" spot, and if this review blows it up, well don't say I never told you anything good! :)
This truck is usually on Olympic near Soto... go east down Olympic past the Sears auto center. There will be two trucks on the right hand side across the street from some housing. One truck, is super crowded (this one) one truck no one is at (don't go there, trust me). If a truck is empty, the food is bad (my taco truck science).
Recently this truck opened a second one around the corner that they serve from ONLY if the first truck on Olympic is too crowded. The menu is as simple as it gets, shrimp tacos, seafood tostadas, ceviche, seafood cocktails, oysters.
The tacos are so good, I can't even really describe the taste... shrimp fried in a shell with a ceviche/seafood sauce on top and lots and lots of ripe avocados layered on top. The seafood tostada (or it could be listed as shrimp and octopus tostada) and the ceviche are both really really good, and cheap.
There area around this truck is like a party-- vendors blasting music, selling belts and homemade pastries. Sometimes I bring my own beer, but I'm usually doing that anyway around that area. The spot is really close to alot of graf yards so if you're out on the hunt stop by this truck for some tacos. I'm pretty certain they are only there on weekends.