!500 is half-ton
2500 is three-quarter ton
3500 is one-ton
W/T is plain jane work truck
L/T and L/TZ are premium trim packages (nicer seats, radio,etc)
Toyota Tundra is a design copied from GMC/Chevy
What you buy depends on what your needs are.....
My horse farm has a GMC one-ton dually, with a diesel, and manual trans, primarily used to pull a fifth-wheel horse trailer...
a half-ton wouldn't be able to do this...
If I was a trim carpenter, the dually would be overkill, I would want a half-ton W/T....