Many people also use the Dayco pullies available at NAPA and other Auto parts stores.
Tensioner pulley Dayco 89007
The 89007 is for a six rib belt, but many people report good results with it and you can use the stock washer.
The Dayco 89016 is actually for the 8 rib belts, but the stock washer does not fit and some have reported interference with the tensioner arm.