my 91dakota LE 4x4is giving me a hum in the drive line and i cant figure out were its coming from i checked all the fluid and serviced the diffs i checked the u-joints they seemed fine to me there was no play there is a clunk when i give it gas and a vibration at about 2100-2500 rpm i believe its all linked together but i have no clue what it is any ideas???

 

iif you have a 2 piece drive shaft I would check the center support bearing it can't be greased and may be simply worn out

 

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