Not sure about the LT2, but my LS required a new door switch and plate. Turn signals, puddle lights, and power folding are bundled in the same mirror (DL3). Yes, they are plug and play. I got my two mirrors off of ebay for $100 + shipping.
After installing, the turn signals will work and the power folding and puddle lights will not. If you want the power folding feature along with the puddle lights, you will have to take to a dealer for the VCI code to unlock the DL3 features within the BCM and also the DDS and PDS.
Some dealers will do this other will not if the vehicle does not offer the DL3 option. The LS model does not offer that option so my local dealer would not reflash. I got around this by exchanging switches with hubby's Silverado LTZ, then took his truck in and the dealer reflashed his truck. Yes, they are the same switch.
I now have turn signals, puddle lights, and power fold.