The fuel filter drain hose (up to the T valve) is cracked on my truck and leaking. What size hose is it really?? Also, can I just unbolt the fuel filter and lift to change it?

mine was 1/4" fuel line. I unbolted the two fuel filter housing bolts to lift it up a little to get the hose off. When in doubt, take the old hose with you to the parts store so they can get the right size for you.