well, for a few weeks now the truck has had a horrible resonating sound around 2000 rpm and I've noticed its been a little rougher and shakier to drive. I got under the truck today and saw that the drive shaft balancer (perfectly cylindrical, attached with a gasket right between the U joints and the back of the tranny) had broken off and is just there rattling around. I have not driven it since I found the problem, but I did note that the truck got rougher and rougher to drive as time went on. It's not horrible to drive right now, but I definitely noticed something was up.
I guess what I'm asking is... what do I do? I've read probably ten different answers on the internet. I've heard everything from take it off and keep driving all the way to replacing the drive shaft. any input greatly appreciated.