'89-'91 OEM SUBURBAN/BLAZER/CREW CAB power mirror assemblies. Then order the the heads from
http://powervisionmirrors.com/gm/gm_models the top 8 listings should fit the bases of the mirrors for our vehicles. When I did the heated turn signal pgrade a few years ago, all I had to do is unbolt the mirror heads from the bases, swap them around and wire them up. And looking at the instructions for these mirrors, They look like a simple swap as well.