I had std cossie 2wd suspension on my last sierra, with 3 door hubs, on 205/50X15, and also to start with the std hubs, went on no problem.
As jon has pointed out these hubs on ebay are cossie, but not 3 door, easy way to tell they are cossie is the area at the base of the strut is filled in, whereas it is sculpted out on a non cossie hub.
Nothing wrong with std sapphy hubs, a lot cheaper than 3 door hubs, and foir what you're wanting just as good, just make sure they are 2wd hubs, 4wd take different struts(thicker body).
tabetha