Vent windows came out in '51. Door handles were changed to pushbutton in '52.
Going only by those two facts, your truck would be a '51.
It's possible the doors were replaced sometime in it's life. Post some pics of the door jamb plate.
What are the engine ID number? It might help in narrowing down the year.
More importantly, what does the title say? Even if it's a '51 and the title says '53, let sleeping dogs lie.
