I have a 2006 landpride zt 60 that I replaced the deck belt 3 times and the drive belt once.
I believe Hustler/Exmark made Landpride mowers, before they decided to build their own.
The Landpride decks look amazingly similar to the older Hustler's.
After complaining, err.. I mean suggesting, about it for the third time, the parts guy at the dealer made a phone call to Landpride.
One of the first questions was had I been mowing with the deck at the 4-1/2 or full height setting of 5 inches.
I said why yes, I had mowed at some point with the deck at that height.
He went on to inform me that Landpride does not reccomend mowing with the deck at these settings.
I asked why? He went on to tell me that they have determined that the geometry between the drive pulley and deck pulleys would not work.
I don't know if this is of any help, but it makes me feel a better.
And no, the dealer did not offer any discount on the next belt.
I no longer mow at any height above 4 inches and have not broken another belt.
Good Luck