Sorry, couldn’t tell from the pic on first glance. I believe the truck was an M35 2 1/2 ton though, not an M54 5-ton. An M54 rear bed is different.
Here’s a few more M54 Quad Gun Trucks
This one is my favorite. I will most likely build it.
Star decals makes a sheet that covers this one and “A Whole Lota Lead” above. They actually do 3 sheets for M54 Quad gun trucks and 7 sheets total that cover just about every type of Vietnam gun truck that was used. Echelon also has five sheets for Vietnam gun trucks.
Lots more info on Vietnam gun trucks in this older thread too.
1/35 M35A1 Quad gun truck - Armor/AFV / Cold War - KitMaker Network