Biff's in L.A. - real or not?

In some episodes of "Adam-12" the officers are shown eating at a place called "Biff's".  Most of the scenes are of the interior variety but there are a couple of shots of the exterior.  The sign features dark script on a backlit rectangular background and I think it might be a drive-in as well as a sit-down restaurant.
 
The interior was almost undoubtedly a set but could the exterior shots been of a real restaurant?  Was there an actual "Biff's" someplace in Los Angeles in the late '60s and early '70s?
 
After "Adam-12" is over "Dragnet" comes on, but so far I haven't seen Joe and Bill eat anything other than takeout from an unseen sandwich shop across the street from the station.
 
Brad