My transmission bumps in my 1988 chevy 1500 scottsdale. It sounds like someone kicks the door when shifting from P to D, or P to R, and vice versa. Also, once in a while while shifting from 1st to second (auto transmission), itll make a quiet noise. What is this bump and why does it happen?

 

Is the idle speed too high? How are the motor mounts? Is there slack in the u joints?

 

mune does that too, its play in the yoke where it goes into the tranny, its not a big deal