Just went through some grief, and thought I'd share - so you don't have to! 
I have an '08 Sierra. I know it was built in '07 though, as the previous (and first) owner ordered it special right when the new body style was announced and he took delivery in/around summer of 2007.
Anyhow, one of my side mirrors must have been hit by a stone or something, as I came out and found it shattered. Got on the ol' Amazonian place and ordered up another, making sure to match shape and year. Well it seems THAT wasn't enough! Here's where YOU get to see stuff, and not make the same mistake I did!
Here's the two types sitting side on side:
The mirror shapes themselves - identical.
To see which one you have without killing it trying to take it apart (as the removal method is very different), I'm suggesting you poke around the YouTubes to see how to remove the upper front portion of the housing. Then, look at where the heater attaches. You can clearly see how one of the rectangles is horizontal, and one vertical.
The horizontal (right side above) seems to be (?) for the later type/style and is quite easy to remove by prying straight up from the mirror side. Those 4 small square holes you can see have little "hooks" that go in and up into that arched area.
The "early" one on the left - that I have, and nobody tells you about - seems to be a left over from the 07 and down. Some kind of mid year change? They're a right PITA to remove!! There could very well be an easier way, but after "quite some time" (grrrr) of struggling with it, all I could do was pry outwards (from the mirror side) and go around with a pick tool from the front, undoing the little plastic tabs until it released. Most of the tabs circled in red here.
Anyhow - after you determine which of the two you have, just make sure to get the right one...first time! You simply can't assume based on the reflective surface shape.
I could only find ONE seller who had this one (there were others similar, but they weren't both this style and heated and had the directional marker). It was DNA Motoring.
Happy motoring! Try to look forward in life, not back (mirror joke).
I have an '08 Sierra. I know it was built in '07 though, as the previous (and first) owner ordered it special right when the new body style was announced and he took delivery in/around summer of 2007.
Anyhow, one of my side mirrors must have been hit by a stone or something, as I came out and found it shattered. Got on the ol' Amazonian place and ordered up another, making sure to match shape and year. Well it seems THAT wasn't enough! Here's where YOU get to see stuff, and not make the same mistake I did!
Here's the two types sitting side on side:
The mirror shapes themselves - identical.
To see which one you have without killing it trying to take it apart (as the removal method is very different), I'm suggesting you poke around the YouTubes to see how to remove the upper front portion of the housing. Then, look at where the heater attaches. You can clearly see how one of the rectangles is horizontal, and one vertical.
The horizontal (right side above) seems to be (?) for the later type/style and is quite easy to remove by prying straight up from the mirror side. Those 4 small square holes you can see have little "hooks" that go in and up into that arched area.
The "early" one on the left - that I have, and nobody tells you about - seems to be a left over from the 07 and down. Some kind of mid year change? They're a right PITA to remove!! There could very well be an easier way, but after "quite some time" (grrrr) of struggling with it, all I could do was pry outwards (from the mirror side) and go around with a pick tool from the front, undoing the little plastic tabs until it released. Most of the tabs circled in red here.
Anyhow - after you determine which of the two you have, just make sure to get the right one...first time! You simply can't assume based on the reflective surface shape.
I could only find ONE seller who had this one (there were others similar, but they weren't both this style and heated and had the directional marker). It was DNA Motoring.
Happy motoring! Try to look forward in life, not back (mirror joke).
