Be aware if your truck didn't come with power extending mirrors and you buy power extending mirrors you need to have some things reprogrammed. There is a thread that talks about what is necessary, if you do a search on "installing power folding mirrors" you should find it.
If I remember you had to reprogram the door modules to recognize them, the cluster, and possibly the BCM but the thread tells you for sure.
If I remember correctly what you do is if you put your mirror selector in the middle position then you can use the arrows to extend or retract the mirrors once they are programmed. It is all in the thread about them and I am only going off memory so don't trust my posting for 100% accurate information on this but it is what I remember.
Rodney