Put an air wrench on them today while I have them out. Top nut is tight, so not sure what was rattling.

 

Well I'm glad you figured out your clicking/clunking sound!... I would vanquish those struts for good and get some solid replacements...Hopefully you can get a defective refund.
The bilstein 5100 is a solid, well built strut/shock that I've been happy with... I still have no first hand experience with the fronts because I haven't had a chance to install them yet.. But the rears have made a night and day difference. They even lifted the rear of my truck about 3/4 inch over my blown out OEM's..

 

I think what I will do is just replace the shock. I think the factory springs are stronger than those Monroe springs, seeing as my front sits higher with 100,000 mi factory struts back in it. I'm done with quick struts for good.
Btw, my friend that sold them to me at a discount, is in billerica for his 4th dui. So much for my refund.