1985 Trans am 305 (lg4) manual, i've got this noisy humming sound coming from the rear end, its more noticable when i apply the gas, i'm talking from around 60km/h and up more so at higher speeds (highway) and also at highway speeds when i totally lay off the gas and just cruise whether in neutral or just coasting bad vibration coming from the seems like the transmission, anyone have any ideas?

 

anyone?....or is this a common thing....?

 

The usual suspects....

Something loose in the drive train; either a U-joint, or the pinion bearings (could be that the big nut needs tightened, in which case the bearings are dead but you're just putting off replacing them for a while), trans yoke on the driveshaft and/or extension housing bushing that it slides into worn