truck shakes while driving, worse when clutch is depressed

I have a 96 Tacoma and have been dealing with a vibration issue for some time now. My truck has a loud vibration noise when driving at speed that worsens when the clutch is pushed in. It sounds like a semi truck using its jake brake though not as loud. I have read that it could anything from CV joints to warped drums. The guys at the Firestone told me that my tires were bad and would never balance so I bought new ones and have the same problem. I have dealt with warped front rotors before and this is not that issue. The vibration does not get worse when braking. Where should I start?

 

Vibrating Tacoma http://www.tacomaworld.com/forum/2nd...one-fixed.html

^^^^^^^ Ask yourself and try this . These are some things you need to try before you post .Not only will it help you troubleshoot the vibration but it will narrow things down for some of the guys that like to try and help you with your vibes .
Does the truck vibrate in neutral and does the vibration change with accelarator pedal ?
Does the truck vibrate while holding the brakes and hitting the gas ?
Does the truck vibrate in neutral at a stand still ?or coasting in neutral ?
Does the truck vibrate in 4x4 ? does the truck only vibrate in 2 wheel drive ?
Does the truck vibrate with the serpentine belt removed ?
Does the truck vibrate with weight in the truck or empty ?
The proper and only way to test for bad universal joints is with the driveshaft removed . You cant tell if the universal joints are seized or tight spots with the driveshaft on the truck . You may see play in the universal joints , but you wont be able to properly check the u-joints without removing the driveshaft .
If you beleive its bad motor mounts or transmission mounts , grab a big pry bar and pry at the mounts to see if the rubber is torn or weak .

 

My money is on bad ujoint on pinion end of rear driveshaft....

 

I've had the same thing almost exactly, Im betting one of the caps on your rear u joint is broken off in the slip yoke. Carrier bearing is also suspect as well.

 

Yup, check the U-joints on your rear driveshaft.