I wouldn't think it would be too difficult on a 2008. mirror harness runs directly into door modules. Driver's door module would have to be replaced. Pass door module might just need reprogrammed. Would have to go to dealer for programming. I have kind of a related question. Has anyone ever added heated mirrors to a 2002 2500HD? the connectors in the doors are already plug and play. Do you just have to replace heater control and mirrors? Sorry if this is a hijack.