Another West Hollywood location. At the time West Hollywood was an island of unincorporated county land inside the city of Los Angeles. I wonder if shooting permits were easier to get from the county than from the city.
Anyway, Nielsen's Books is at 7308 Melrose Ave. in West Hollywood. Enter that address in Google Maps and you will see that Nielsen's is now something called "The Monkey King" and Caroline Cleaners next door is now something called "The Bling Jewelry Company." Some features on the buildings are still recognizable if you look carefully. When Nielsen and Mathews walk out of the book store at 7:05 they are walking east on Melrose with Fuller St. visible behind them. Later when Mathews drives away we see the east wall of the book store with the phone number and street address visible. It also says Back Numbers above, which is an old fashioned way of saying "back issues." I wonder if the bookstore really was called Nielsen's, because that''s a pretty substantial looking sign out front.
At 10:00, just after "Larry" completes his call to Nielsen, the two con men stand at the southwest corner of Melrose and Poinsettia Place while conferring. Floyd's Barbershop now stands on this corner.
The chase scene late in the episode looks as if it's mostly on Mulholland Drive near Laurel Canyon Blvd. - but that's just a guess.