I was actually looking for pictures of Mack Trucks when I stumbled onto this one titled "Aerial view of the Mack Motor Truck Company in Los Angeles, ca.1925".
USC Digital Library
A quick look through the City Directories, and I only found an address on E 7th Street that didn't look right. Then I tried searching for "Hammond Lumber" which appears on the roof sign of the building across the road. That stood at 2010 S Alameda. Imagine my surprise when I found the whole Mack Trucks factory still standing at 2001 S Alameda (albeit without the watertank).
Google Maps
The front and rear buildings now belong to Forever 21.
GSV
Here's the Hammond Lumber Company advert from the 1926 CD.
rescarta.lapl.org