I have a problem with a viberation and acts like a drive shaft out of balance,have had a new drive shaft installed and now does it at a lower speed on a 2014 silverado 1500 on a 5.3 eng. any help

(1st) Check the engine and gearbox mountings.

(2nd) Check the brake-disc's if it needs to be sceemed.

There are many stages of vibration. The most common is in the steering and USUALLY a steering dampner will correct this. However, your description is not real defined and until the technician actually experiences it, it cannot be properly diagnosed

3 things that i know of that could cause vibration noise that starts/stops at speeds. 1- The tires, either they need balancing, or they got used up irregularly and "bounce" on the pavement. 2- drive shafts are damaged (dented, waved), dirty, or need balancing. It happens from time to time that the weights the solder on the shafts to balance them at the factory just fall off due to rotation and rust and all, and just a good clump of baked on dirt can also unbalance the shafts. 3- U-Joints that need replacing don't let the shafts move freely and tend to make them vibrate. If that is the problem, you can replace the u-joints with new ones using a few tools to remove the snap rings and a hammer or vice to press the u-joints out of their sockets. Also i do believe the front end on a liberty is made basically like a FWD and has 2 half shafts to drive the wheels, and the joints in those can also be done for and need replacing, although half shafts don't have u-joints and aren't really serviceable so if the problem is there you will need to replace the whole half shaft. Hope this helps.

did u check your wreck ends and your boll joints?

ur rite probly worn--also shocks are leading cause of moving vibration--2nd would be drive shaft

Your flexplate and/or torque convertor are out of balance.
If recently replaced it should be a warranty issue.
By your testing you have determined it's transmission related.
I have seen new/rebuilt torque convertors be balanced incorrectly.

Do you mean u joints because there is realy not a bearing in the driveshaft so to speak But the u joints have neddle bearings in the yoke You need to unbolt the drive shaft from the rear cairrer then pull it back out of the transmission tail stock it will laek some oil you can take a plastic bag and a couple of rubber bands and seal that up Then take the shaft out from under the vehicle to some place you can work on it like a bench but when you remove the shaft make sure you mark it its weighted and needs to go back in the same way or the balance will be off and it will viberate at certion speeds There small c clips that need to be removed from the out side of the bearing caps then you can press or drive the oid yokes out a little head helps something propane torch you don,t have to worry about the old ones When there out this is the tricky part you need to remove two of the caps from the new joint oppiste sides there pregreesed and the bearings will stay inside of them slide one cap into the drive shaft then slide the u joint yoke into the cap from the inside and gentle puessit on the yoke then do the same with the other side of the cap on the oppiste side of the driveshaft you can use a large c clamp to press them into pisition install the new clips and gresse if the unit has a gresse fitting and you will save a lot of money if you can do this Then install but make sure you put in the same side up as you took it out

To Install:
NOTE: Clean balancer belt drive pulley, timing belt pulleys and upper/lower timing cover prior to belt installation.

1. Set timing belt drive pulley to TDC by aligning dimple on pulley with dimple on oil pump.
   
   
2. Set camshaft pulley to TDC so that "UP" mark is at top and grooves align with top of cylinder head. Timing belt installation
   
   
3. Starting with driver pulley, install timing belt in a counterclockwise sequence.
4. Loosen and ten retighten adjusting nut.
5. Install balancer belt drive pulley. NOTE: Inspect rubber seal on lower cover and replace as necessary.
   
6. Install lower cover.
7. Install crankshaft pulley and bolt.
8. Rotate crankshaft pulley counterclockwise several times to seat belt.
9. Loosen adjusting nut 1 turn.
10. Rotate crankshaft counterclockwise 3 teeth on camshaft pulley.
11. Tighten adjusting nut to 33 ft lb (44 Nm).
    
    
12. Turn crankshaft pulley until TDC is achieved.
    
    
13. Ensure that camshaft pulley "UP" mark is at top and grooves align with top of cylinder head.
14. Remove crankshaft pulley and lower cover.
15. Rotate crankshaft to TDC again and lock timing belt adjuster arm with a 6 mm timing cover bolt.
16. Loosen adjuster nut 1 turn and ensure that belt tensioner freely moves.
17. Push tensioner up and tighten adjusting nut. Balancer shaft alignment
    
    
18. Remove bolt and washer from maintenance hole.
19. Using a 6 X 100 mm bolt, scribe a mark 2.9 in (74 mm) from end.
20. Insert bolt into maintenance hole and hole in balancer shaft.
21. Install bolt up to scribed line. Balancer shaft alignment
    
    
22. Align groove on balancer shaft with pointer on oil pump housing.
23. Install balancer belt and loosen adjusting nut 1 turn to tension.
24. Retighten bolt. Balancer shaft alignment
    
    
25. Remove bolt from maintenance hole and install bolt and washer. Tighten to 22 ft lb (29 Nm).
26. Reinstall crankshaft pulley.
27. Loosen adjusting nut 1 turn.
28. Rotate crankshaft pulley counterclockwise 1 turn and tighten adjusting nut.
29. Remove bolt from timing belt adjuster arm. NOTE: Inspect rubber seal on lower cover and replace as necessary.
    
30. Remove crankshaft pulley.
31. Install lower cover.
32. Install seal at adjusting nut. NOTE: Crankshaft pulley, bolt and washer must be cleaned prior to installation.
    
33. Lubricate crankshaft pulley bolt between head and washer and bolt threads with clean engine oil.
    
    CAUTION
    Do not use impact wrench to perform following step.
    
34. Install crankshaft pulley and tighten bolt using special tools to 181 ft lb (245 Nm).
35. Install dipstick/tube assembly.
36. Install upper cover. Tighten bolts to 9 ft lb (12 Nm).
37. Install cylinder head cover.
38. Install alternator bracket and alternator.
39. Install power steering pump belt and alternator belt. Upper bracket installation
    
    
40. Install upper bracket and tighten fasteners in proper numbered sequence.
41. Install stop.
42. Install battery and enter radio anti-theft code.

drive shaft is bent do to instalation of u-joints. get shaft balanced both pieces together.

Hesitation,jerking,acts as if it's not getting fuel? Have the egr/coil checked! I had same problem,thought it might be injectors,after delving deeper into it,I found the coil was defective