http://www.ebay.com/itm/Fan-clutch-tool-for-Trailblazer-Envoy-/151839269910?vxp=mtr
I bought one of these to hold the pulley while I broke the fan clutch nut loose on my Trailblazer and it worked better then similar tools that cost 4 times as much - even the J-41240-1 from Kent Moore! This definitely gets my seal of approval.