Hi Mattie,
if you've not yet removed the existing belt you can loosen the tentioner a little then push the existing belt as far on as you can, then fit the new one along side, once it's in position you just cut the old one off with a stanley knife, then push the new one into place retighten the tentioner, hey presto! saves a fortune,
I've done it countless times without any problems.
Terry Sim
Terry Sim, February 2009