Grinding vibration feel in drive train AWD when foot is off the gas pedal

[crunchie_frog]

Without the front drive shaft, smooth, no noticeable vibration. With the front drive shaft (I have tried 3 different drive shafts, one new, two rebuilt), and I get a grinding vibration type feel that gets worse when I take my foot off the accelerator or put in neutral. Transfer case is from a salvage yard but I have verified all 4 wheels are turning on jackstands and I cannot spin the tires on wet roads accelerating like I can when the front drive shaft is removed (2WD) so I am thinking the viscous coupling is okay. I am thinking it may be a bearing in the front differential or in the transfer case. I have not been able to detect any horizonal movement in the bearings but I cannot tell for certain. I am planning on draining the transfer case in clean pan and see if I can see any metal and I also am going to double check for any horizontal movement of the front drive shaft at both ends.

Any ideas about what could cause the grinding vibration feel?

Thanks,

 

[Fix4Dirt]

bump

 

[donalds]

Sounds like a pinion bearing to me

 

[crunchie_frog]

Sounds like a pinion bearing to me

Thanks, yes, could be, I should have the chance this long weekend to get underneath it and see if there is any play. I guess there are two options, one in the front differential, the other in the AWD transfer case, has anyone every replaced either of these?

 

[donalds]

Don't worry help is on the way
These people on here are absolute pros

 

[crunchie_frog]

There is horizontal play in the yoke coming out of the front differential that connects to the front drive shaft. I think this is the issue. It sounds like the pinion bearing and this is a drive line shop issue and not really for the home mechanic. Comments/experiences?