heres something different beside my 84 i also have a 85 longbox 3+1 overdrive manual this is my trash truck however there is something wrong with the clutch or trans when its in nutral the truck shakes and the trans makes this horrible noise but when i engage the clutch it stops any ideas?

 

when you say engage the clutch to mean pushing the pedal to the floor or releasing the pedal...

 

Sounds like you have a bad throw out bearing.