Eric,
The 851, 888, 916, 996 and pre 2002 748 use the same belts.
I don't know of an alternative to the belt tensioner, but you can buy it cheaper than Ducati sells it.
I bought my tensioner here.
http://www.ca-cycleworks.com/shop/ca...ati/maint.html Chris also sells Bucci timing belts which are much cheaper than original Ducati belts.