My Canadian parts manual has numerous listings for the drag link, and some of listings group the 1 1/2 and 2 ton together. What is the year of the truck, does the pitman arm have a forging number on it? Maybe I can narrow it down a little more.
3B also has a parts book, and maybe he has a better idea of what works and what doesn't. My guess, is that you could probably use the 1 1/2 ton drag link.
Bob