Trans problem

I bought a 1994 Cavalier RS convertible for $750, it has the 3.1 V6 in it with the 3 speed auto, it has 130,000 miles on it, the body is near perfect and well my trans is kind of scareing me, when ever I shift it into D it kind of slams it, if doesn't hit as hard if i bring it to Nuet and take my foot off the brake and shift, but it has a noticable slam, i have all new fluid in it, it doesn't miss and i even have taken it up to top out, which i am not sure IS top out because the speed needle was laying on top of the odometer housing, the car runs fine, no gear slipping, it's just that sound, is that normal? and another thing what IS the maximum top out of the 3.1 convy?

same stupid thing happened to my 00 cavalier check all your sensors. one faulty sensors will mess up everything.