transmission is doing a bit of knocking

I get a loud hammering noise when accelerating with any quickness preceded by a shaking from the transmission. The knocking noise is very pronounced and seems to be coming from right below and in front of where the stick is in the car. Also happens if trying to climb an incline. Have to let the car slow while climbing and then pick up speed on opposite side. Very loud. Very pronounced. had the clutch rebuilt about 2000 miles ago.

Thanks for your thoughts.