Cadillac Repair: transmission, radator, jackstands

Question
First of all thanks
Yeah I noticed before when me and a friend were looking at it, when i shift the gear from park the engine jumps. I forgot to tell you most of the time it jerks is when i shift from park to reverse and sometimes netural to drive.  My question is are the mounts your talking about by the radator the motor mounts also or are they transmission mounts. becasue like I said i changes a motor mount awhile ago that was broke. but i only changed one. Also it has been doing this for about 4 years now, i dont know if that would help determine if its the mounts or has to repaired cause of that cusion.
thanks again  

Answer
Hi Alex, If the mount attaches to the engine then its an engine mount. However the mount next to the radiator is called a LH or front engine mount and the other one is a LH or Front trans mount. Alot of times if say the LH engine mount is bad then the LH trans mount is also and it would be good to replace them both. What you need to do is get your car up on jackstands and have someone shift to reverse and drive with their foot on the brake and with you under the vehicle you should be able to tell what mount is bad. Otherwise take it to the shop and have them look at it to tell you and then you go ahead and replace the bad mount. Hope that helps. Bill