Fair enough! I found two pictures of the Kenworth Tank Wagon and two of the GMC they had, I also found some brush "tankers" which would be pretty useless as none of them had anything over 400 gallon water tanks. I did however find pictures of the early to late 1940s Mack 45u COE tankers they had, which had around 600 gallons of water on it.
. http://www.usfirepolice.net/ca_california/ca_lafd/ca_lafd_retired_tanker.html
http://www.usfirepolice.net/ca_california/ca_lafd/ca_lafd_retired_brush.html