I'm searching for a used FCM as mine is bad. I've gone onto realoem.com to look up interchangeable part numbers. I've had no luck with bilaterally exchangable part #'s, i believe the restrospectively ones will not work is that correct? also, will the bilaterally still need to be reprogrammed to my vin, or is that only if I get one that is not listed as interchangeable? Sorry, I'm just a tad confused on that part. Thanks