Mine has the spin on Duramax fan not the bolt on like yours. Greg from BD made a big song and dance about changing the original pump to this 'the latest you beaut' pump. My original veebelt driven wp has the fitting like yours, but not the new one. Greg is not responding to me after I gave him a serve about the bonnet and body lift fiasco, so will try later this week for an answer when Scotty returns from sick leave.

Your motor looks good. Did you have to relieve the top of the thermostat housing to allow the s/c snout to fit? What size alternator are you running? When is the motor going into the vehicle or is it already in?