How do I fix automatic transmission, loose shifter linkage; making metallic clinking noise when shifting from reverse to drive?

SOURCE: Can't shift into reverse ( manual transmission )

I have the same problem on my 2005 cts. The shifter fork has two rubber bushings that attach at the transmission that break or give way. I assume they did this for a softer feel and to avoid vibration but it leads to the selector not engaging well when you go the extreme direction of reverse on the shifter as there is too much deflection. I replaced the bushings with washers as spacers and it seems to work as a "McGyver" fix. I do intend to get the parts needed from Cadillac to restore it to factory standards. Hopefully they have the parts. To fix the problem you have to go under the car. To get good access you have to disconnect the exhaust and the driveshaft. I did it without this and just tormented my poor hands but I wasn't willing to do all the other work while in my driveway. You simply take the clip holding the fork shaft onto the transmission selector end off and slide the small shaft out. I also took off the shifter side of the fork to study the thing a bit better. That takes a 13mm and a small allen wrench, 4.5 or 3/16, can't remember. Then replace the bushings or do as I did and stack some washers so as to get rid of the slack between the inside of the fork and the gear selector on the transmission. Assemble and try. If you have as good dexterity and tenacity at your fingertips as I do, you'll curse the day you attempted doing this without taking out all the other stuff. If you don't, take out all the other stuff to make room for your hands. The space is very confined. Good luck.

SOURCE: 2003 Cadillac CTS. Shift linkage makes metallic

Just had the same problem. The problem is that the rubber bushing on the transmission linkage deteriorates and falls off. This causes two problems - shifter is loose and a metallic clunking sound is heard when shifting. It's not the shifter inside the car. It's the linkage underneath the car. You have to buy the bushing (if sold by itself) or the linkage kit. The linkage is on the passenger side of the transmission between transmission and right side exhaust pipe. Ensure engine/exhaust is cold prior to trying to access. Regards.