I replaced both my drive axles, I think they're about $50 each not including core charge. I'm not sure how to diagnose wich is bad, but I think its a good idea to do both at same time

 

You're in for a nice surprise, all that "((Shaking))" will be gone when you replace the drive axles. But a word of cautition...that was the "cause" there might be damage to the tie rods (just change them $30 each) and possibly to the bearings.
More cautition- my SS didn't have the right instructions on how to remove the axle, I had to remove the 2 strut bolts for enough play to get it out...hopefully urs will come out the hole like the book says.
One "wiggle" in the front end tends to loosen the other parts, best to just replace them all @ once and be done.
Good Luck!!
Mouse

 

I want to thank everyone who offered advice on my Monte Carlo that was shaking so badly. I want to report that I had the front drive axles replaced and the Monty is running smoothly! thanks for all the help.

MonteMadness

 

awesome to hear!