These are the only Caltrans owned Form 400s i know of in the Los Angeles area. There are still a small handful of othee clamshells such as OV-20s, Ovalites, etc. I remember clamshells on the Bay Area freeways long ago, like almost 30 years aho!
cool there are some double guyed poles simular to these on interstate 37/US 281 in San Antonio, Texas was MV but got HPS FCO junk on them but the poles remains.