need a new drive belt

i have a hustler with 440 and no idea what size belt i need. it came with 3 belts but 2 are definitely too small and the 3rd although looser still has enough drag to spin the trans enough i cant shift it into gear with the engine idling.
i did search here but there was a ton of results and i was hoping yall could help so i wasnt spending hours reading irrelevant posts.
thanks!

Google "quality Drive Systems" they are out in California and ask for Roy. He need to know the diameter of the clutches and the center to center distance of the clutches. He can help you get the right belt size. Good guy to talk to, he is recommended by many members.