07 sel huge vibration
 

Hey guys this is my first time posting here although I have trolled here for awhile now I need your help. My wife's 07 sel fusion sometimes gets a huge vibration that's not in any wheels it doesn't happen al the time either. There's 140000kms on the car. So after I checked all the wheels I was confident it was something to do with the rear driveshaft. So I took it to the local mechanic and after about 4 days of "I'll get a chance to look at it later" he calls my wife and says tranny needs rebuild. ??? In my opinion the car shifts fine, no slippage what so ever. Has anyone had this problem before? I really don't think its the Trans, in my opinion it seems like the driveshaft going out of wack or could very well be the tourque converter locking and unlocking but not the transmission. Any advice on this issue would be greatly appreciated

Get a second, and even a third opinion from other auto techs non-affilated with the first. Don't even tell the other mechanics what the first mechanic said.