I have an 88 deville but neways i was wondering what causes a slamming sound when i put it into gear sometimes?...Yea but also i need new shocks or sumthing...my car sits up higher in the back and when i put just 2 10s and a box in the trunk its level with the front...i dont think that should cause that much difference...any suggestions...oh and also what kind of brakes are reliable

 

I have had the condition I think you're describing on a number of GM cars as they age, including Cadillacs. I'll bet you it's a motor/transaxle mount. They're soft and they deteriorate taking up all the shock and weight. You may also have the sensation that the car is slightly lurching foward or up. Have them all checked; a bad one's easy to spot, and I haven't found it to ever be a particularly expensive repair.

 

However, if all it's doing is making a slamming sound, you could have a problem in the transaxle too!