okay so I am online looking at 2004 explorer rear driveshafts and none of them show this weight, of course
However I am used to seeing this sucker on full size trucks like super duties and the like
Not sure why your 4.6 explorer has one.
Typically the weight is 6" or so away from the universal joint yoke. It appears that your weight may have slipped?
They are usually mounted with rubber melted in there, the rubber gets old and brittle and cracks
If it was my driveshaft I would likely just try to slip it off the end or cut it off and see if any vibrations ensue
Ill spend a few more minutes searching like 03 and 05 to see if we cannot replicate this shaft.
I just crushed a 05 explorer, but it was v6 and 4wf, it did not have this weight.
Usually full size trucks do, so I am used to seeing them on rear driveshafts of fords