driveshaft/ rear diff problems.. solution??

hello! I have a 1991 toyota pickup 4 banger 4x4 22re. my drive shaft wobbled like crazy and i had a whine on deaceleration.. I got it fixed, it was a bad pinion bearing and my driveshaft had no play at all. A week goes by and i have the same sound and now my driveshaft wobbles just like before. i also have a vibration at 45, and 65. could it be related to the same issue? I dont want to sell it, i put a decent amount of money in it to make it alive again. I dont really know what to do. It also whines in neutral but not as loud at all. seems like when its under load its crying for attention. the vibrations is always at 45 and 65 even when in neutral. I know this is not the correct place to post, but in desperate need of advice.
when the mechanic replaced the bearing he checked everything and said everything looks good.
but something is causing that pinion bearing to break but i dont know what..
what can cause the pinion bearing to break after a week of driving?
bent axle?
anything would help. thanks guys and gals

 

Are you saying the pinion bearing is bad a 2nd time?

It can be A LOT of things and multiple things: Off the top of my head....

It could be suspension related - check all suspension components including bolts (tight?), eye bolts (tight & lubircated?), centering pins (not broken?), shackles (too tight? Locked up? Lubricated?).
Check and lubricate Ujoints.
Check driveshaft for missing weights/bends/etc.
I'm not familiar with the older tacos, but check the everything between pinion & t case/transmission.
Wheel bearings OK?
How's the ring gear? When was the last time you changed the oils in diffs?
When was the last time you had your wheels balanced?

 

All fluids changed recently and the bearing is bad the second time. I know my front wheel bearings are bad, tire rocks back and can hear it on slower speeds. No clue when wheels were balanced tires are not the greatest. Bought 3 months ago so I think po didn't rotate or balance wheels
Thank you for the response!!!

QUOTE="Janster, post: 11562185, member:

1138"]Are you saying the pinion bearing is bad a 2nd time?

It can be A LOT of things and multiple things: Off the top of my head....

It could be suspension related - check all suspension components including bolts (tight?), eye bolts (tight & lubircated?), centering pins (not broken?), shackles (too tight? Locked up? Lubricated?).
Check and lubricate Ujoints.
Check driveshaft for missing weights/bends/etc.
I'm not familiar with the older tacos, but check the everything between pinion & t case/transmission.
Wheel bearings OK?
How's the ring gear? When was the last time you changed the oils in diffs?
When was the last time you had your wheels balanced?[/QUOTE]

 

did you replace the bearing or did a shop do it?

 

Shop did it