I've been thinking about this too. One of my work vehicles is a 2002 Silverado 3500, the rear view mirror is self dimmimg, also has temp and compass displays. Every time I'm driving it I wonder how much of those mechanisms are self contained and how hard it would be to fit one to my runner... maybe someone here knows?
PS not so sorry for somewhat hijacking this thread
PPS - I think OP is asking if there was ever a 3rd gen with a self dimming mirror and if they could swap it out easily if so. Not an expert but I don't think that was an option.