I have an old truck that I've owned for a number of years ! It used to be my daily driver but it got to where the engine didn't run very well and it had a terrible amount of chattering when you tried to pull out no matter how easy you tried to do so . I always figured it was the clutch or flywheel causing it . As time went on , it was relegated to the garage and I drove my car everyday. About two years ago , I thought it was time to revive that old truck . I bought a V8 to replace the old tired 6 cylinder . When I pulled it out , I was surprised to find the actual cause of the chattering ! The bell housing was missing two bolts and the rest were loose ! When the new engine went back in , with the correct amount of bolts tightened to the proper torque , the chattering was gone ! My be worth checking your bell housing just to be sure !