i used to have those exact same tails in CF, not chrome, until someone stole them off my truck a little over a month ago...but yeah i really liked those tails. The big middle lense is for the stock brake/running/signal light and the bottom lense is for the reverse like you are saying. The tails come with a plug for the top lense if you dont want to use it. I on the other hand wanted the lights fully functional so i tapped in another reverse socket with a RED bulb into the signal/brake light wire so that it was functional. So then the top lense was just like the middle lense minus the running light function....makes breaking and signaling more noticable to traffic around you...a benefit IMO.
2002 Oxford White EDGE
4.0L SOHC V6
(auto) - 207hp - 2WD - Extended Cab - 3.55 LS - Power Everything - 6CD In-dash - Towing Package - Style Side Bed
A Few Mods Here and There