These "Fire Musters" are cool. Dad was a volunteer for 13 years so I have a connection. The truckers on the board should find them of some interest also.
Reminds me of a "Little Golden Book" I loved as a child called "The Bravest of All." I tracked down a tattered copy on Amazon and bought it recently and sometimes read it to my kids.
Theres a dude in Tamaqua PA has a couple A100ish firetrucks. I think they were called A600 or something. If you need parts for the '64-'67 flat faces, he's your best friend. Nicest guy you ever met, too!
You are thinking of the L600/L700 series, which incorporated most of an A100 cab, but are considerably larger.
The A100 series were in production from 1964 - 1970. The L600/L700 series ran from 1966 through 1970. Both ran their course without any major changes to trim or options. It's pretty hard to tell a '64 from a '70, other than the sidemarkers on the '68 - '70 vans and L600/L700 units. Below is a '70 L700, as judged from the rectangular truck/van sidemarker on the cab.
Our nearby tech Museum harbors quite some fire apparatus including a good number of American iron. Most fascinating those ladder trucks with a seperate steering System on the back that had to be actuated by a second Person. Must have been a bit adventurous in the big cities.