That sounds like a bearing, and with the new WP bearing, I wonder if that's it. Don't sell it just to get rid of it, that $2500 is way to little for a complete and driveable 2nd gen.
I would be satisfied with a normal WP versus that electric high tech version. I know small power gains are nice, but at what cost and is it reliable long term? I have an electric fan in my 99 work truck, it's been great but I worry about it a lot compared to the tried and true OEM fan and clutch. I will still convert my other(project) 98 to an electric fan, but I'll put a lot of time and effort in it to be sure it's reliable.
BTW, I just ordered a new WP from Summit for my project truck, the FlowKooler brand, I have used OEM for my two past 302 WP's.
Free Shipping - FlowKooler Hi-Flow Mechanical Water Pumps with qualifying orders of $109. Shop Water Pumps, Mechanical at Summit Racing.
www.summitracing.com