I am trying to determine if my timing is broken.

Try to start the truck will not hurt it. If it cranks real fast and does not start, it's probably the timing belt. Belt is recommended to be replaced every 90,000, miles.

First thing - your engine is a Non-interference type / this means the pistons wont go crashing into the valves when the belt breaks! 90k miles is the recommended interval for changing it! Check the tensioner and idler pulley too if they have any play replace them too! You dont want timing problems and have to do this tear down again! If this engine were an interference type you would be looking at replacing the entire engine! Most manufactures have moved to timing chains (they tend to last a long time typically the life of the engine if not abused) because consumers have complained about the cost of maintaining a timing belt made of rubber and kevlar! My daughters 2003 4runner cost $950 to replace it plus the other components mentioned! Yikes! Hope this helps! interference engine is. A piston in the engine goes up and down, on the down stroke the valves (either exhaust or intake) open and let in fuel and air or release exhaust. Sometimes engineers like to put a little more clearance on the valves to get more air and fuel in. Also engineers like higher compression ratios. As a result sometimes the valves go below the line where the piston goes on its powerstroke. This is not a problem until the timing chain or belt breaks. When that happens you lose all compression, the valves come to a stop, but the pistons keep moving until you come to a stop. Some valves will be open and when the piston goes up, ouch. Bent valves or worse. The big point being, if you have a interference engine, as I do in my Honda and Acura, when it comes time to change the timing belt or chain, YOU BETTER DO IT.