yea my truck did that and it turned out 2 be the drive shafted. someone didnt put the some clips or somehting in it and it fell off when i was driving one day

 

yea i agree about alignment for sure, but I dont think that is my problem. Ill check it out tomm., but I spend alot of time under my turck and havnt noticed it yet, but Ill make sure. Thanks for the help

 

I had the same issues with my 00/z71 back a few years ago. There are 5 TSBs on it. There is slack between the yoke on the driveshaft and the tranny. It took out my rear end and snapped my driveshaft. GM replaced everything. If your out of warranty, they will still fix it as it is considered a path to an accident. I posted the TSBs about 2 months ago for a few other guys who were starting to see the same thing. I'd suggest you look at my older posts but the pages are gone. Just GOOGLE silverado+driveshaft+TSB+shake . You will see what you need to get the problem resolved. Over 93k Silverado owners have had the same problem. Makes onerealize what it actually takes to get GM to start a recall.
GL
Greek

 

alright, thanks for all of the help. How much will this cost me though??

 

for the speed specific shakes or shift point shakes, you might look at your tourque converter. I had an old mustang that would scramble your brains at 32 mph and stop with more or less gas. constant vibrating is the drive shaft though.

just my 2 cents...

 

Get an aliainment, but the way you are describing the EXTREME shacking, it could defintly be the driveshaft. I am very curious please let us know what happens.

 

try getting the transmission looked at or serviced could be the torque converter