Yeah, you stumbled upon something that I've found out (rather inconveniently) in the past couple days. lol
There were 2 basics types of the rear calipers as found on the Focus - which you have illustrated nicely.
The SVT style ones have those lower bolt holes to clear the larger rotors.
The other calipers you have shown are found on the regular Focus' from 00-07 that came with the AdvanceTrac option (rear discs) as well as on the Focus ST sedan
April 2010 ROTM
2011 Yellow Blaze Metallic SES Fiesta hatch
Carlisle All-Ford Nationals 2011 1st Place - Fiesta Class