car “clunks” at times when shifting at very low speeds
Looking at a couple of Cadillac forums it appears to be a common problem, to the extent that some owners accept it as “normal.” That said, check the transmission fluid if possible. (I don’t know if your SRX has a transmission dipstick or not.) A broken engine or transmission mount could also account for the noise. There might also be a reprogramming procedure needed, a dealer would know. Good luck.