How do I replace the belt on the deck of a Sears GT6000--44" deck?

Hi,
It is always wisse to furnish the 9 digit model number with a question. The Gt6000 has been made at least since 1990 all the way up to present. The positive part of the question was the mention of the 44" deck which dates to the early to nid 1990s and was replaced by the current 46" deck. Most of the newest machines sport a 54" deck.
Both the 44" and 46" decks have the same basic two belt configuration and routing though different length belts running their three blades. There is an older two blade deck that I do not believe is an issue.
Thanks to a website ssbtractor.com, I came up with the possible model numbers, 917.255910, 917.255950, 917.255960, 255981 and 917.257720.
All seem to have their owners manuals online at managemylife.com though the last one includes a parts breakdown. It says the belts are part #131264 for primary and part #131290 for secondary. The picures folow and direction and manual are at:
http://www.managemylife.com/mmh/lis_pdf/OWNM/L0904392.pdf
Peace,
Clarke