OK guys, I know this ain't the sexiest topic in the world, but... I just looked at a freshly rebuilt Ford V6 shortblock that the owner swears is a 4-liter. Trouble is, it has a distributor mount on the back like the 3.8 in my old Aerostar. It appears to have a 4-inch bore, by the way. Casting #'s are C851A 90TM6015 AB. What engine is this?