Below is a list I compiled from various sources that I believe to be accurate. There may be a plant or two I have missed, however.

Bob Chaparro

Hemet, CA

++++

Southern California Automobile Assembly Plants

 Chrysler

Commerce, 1929-1971

Ford

Pico Rivera, 1957-1980

Long Beach, 1930–1959

General Motors

South Gate, 1936-1982

Van Nuys, 1947-1992

Kaiser Frazer

Long Beach, 1947-1955?

Nash Motors

El Segundo, 1948-1955

Studebaker

Vernon, 1936-1956

Toyota (Truck Beds)

Long Beach, 1972-2004

Willys-Overland

Maywood 1928-1954