I figured the Mack Tankers might not have made it, I think the newest Mack was a 45ish, perhaps we could keep counting down in the project nostalgia mod to be 40s-60s, would that be interesting!
Anyways, I think the Oshkosh and GMCs had to have made it to at least the later 70s, I know an oshkosh made it until the late 70s. Here is a picture of it below.
http://2.bp.blogspot.com/-0IjRaIUCXhw/VQygseTzneI/AAAAAAABLRM/LBTcJc5L6lE/s1600/1955%2BOshkosh%2B1000%2Bgallon%2BLAFD.jpg
I also found two more older tankers, not LAFD but same type they used.
http://www.eastherkimerfire.com/wp-content/uploads/2010/04/GMC-TANKER.jpg
http://www.eastherkimerfire.com/wp-content/uploads/2010/04/1952-TANKER.jpg