I am by far no pro, about anything but I had an idea and no one shot this to you yet. My issue in 3 gear it was RUMBLING like a mother it sounded like my tranny was gonna drop from my car and if i clutch in and gave it gas a little it would stop. My issue was U-joints..... I got a new allu drive shaft with u joint built in. It stop no issues rumbling is gone... it isnt hard to check them so it isn't a bad deal. I hope that what it is ez fix =p