Can't specifically say for ORD, but there have been MANY more GM large SUVs in rental fleets than Fords in the past year or so. FMC came out with the new Expedition and Navigator and have had trouble fill-in orders for non-fleet sales (higher margin) so they've sold very limited quantities to fleets. You might get lucky (at least in your opinion) and snag a FMC version but I wouldn't hold your breath as I'd say a GM is much more likely.