Hello Jordan,
It is what was known as a Sandwich Car.
The reason for this is in fact apparent from the photo you sent in.
The rear armoured plates are in fact made up of two plates of steel with what I believe was a wooden layer in between.
The Israelis had only limited access to armoured plate in 1947 and 1948.
Many of these trucks were used to take supplies and men from Tel Aviv to the Jewish enclaves in Jerusalem.
Many ambushes were made on these trucks in the pass up past Latrun.
You can see the rear of one of these trucks in the following pictures..
2429.16 | BATTLE OF THE ROADS aka TROOPS IN ACTION PALESTINE (1:42:19:00 - 1:45:25:00)
A post war picture shows one with an open roof, they also had closed roofs, and wirenetting covers on others.
2461.17 | MILITARY DEMONSTRATION IN ISRAEL (1:47:27:00 - 1:55:56:00)
There is information on some of the actions these vehicles took part in on the following sites.
http://www.jr.co.il/pictures/israel/...y/jrilh003.jpg
http://www.davidpride.com/Israeli_Ar...or_battles.htm
http://www.ohav.org/columns/survival/solomon3.html
Regards
Nick Balmer