Our 04-07 CTS-V Transmission Mount is a direct replacement for worn/sagging factory transmission mounts. While bad transmission mounts do not have the obvious signs of failure that most other parts have, when they do go bad they can cause other problems both immediate and long term.
The main purpose of the transmission mount is to hold the rear of the transmission at the proper height, which maintains proper drive shaft alignment and shifter linkage geometry. Immediate problems could be difficulty in shifting. CTS-V owners have described difficulty putting the transmission in reverse, sometimes first and sixth have been reported, but reverse has been a universal complaint.
The long term issues will be undue stress put on the drive shaft coupler, which transmits the torque from the transmission to the drive shaft, the pilot shaft, which aligns the transmission to the drive shaft and the carrier bearing that supports the rear end of the front half of the drive shaft. While not imperative, it’s a good idea to replace the transmission mount at the same time that the engine mounts are replaced. This way all three points of contact that support the engine/transmission assembly are up to par.