Why does my car sometimes Bang into gear violently when switching from reverse to drive

What is your question?

Doesn't happen often. Maybe once out of every three to four times I drive the car. Car only has 34,000 miles on it. This problem began when it had about 15,000 miles. Hasn't gotten any worse since it started. 2006 Monte Carlo 3.5

What makes this problem better or worse?

Nothing

How long has your 2006 Chevrolet Monte Carlo had this problem?

Since 15000 miles, six years ago.