It could be the oilpan seal too, make sure you double check when doing it. If it's the oilpan there shouldn't be any oil in the little ledge right below the crank timing pulley.
I'd go with the Ford one next time, I think my seal from Napa was Timken and it was a PITA to install, really stiff and hard to get it in. It was $11, so a bit cheaper, but don't skimp if you don't have to.