00SS6886

I have a weird noise and a vibration coming from the rearend when I get on it in first and second. Normal driving is fine and dandy, but hit her hard and you feel and hear something that I really can't place. Anyone have any ideas or experienced this themselves? Also, my clutch feels really heavy for a couple seconds if I shift really hard. What could that be? 42K and rarely driven ***** to the wall. Any help would be great.