There is more than one model of 2 ton trucks.
You need to know the model..H, HH J, K ect. to figure out drum and Shoe width specs. No over size is mentioned although .060" is usually max but on large truck drums the OS is sometimes more. A good truck shop should know.
The only 2 ton trucks with 16" front drums are the heavy duty two ton J series trucks. Shoe width is 2-1/2"
Rear drums on all models of two ton models use 16" rear drums... depending on model 3" or 3-1/2" wide rear shoes are used.
Pull the drums to be sure of what you have.