Any way to tell an E-68 HP 400 from an E-64 standard 4bbl 400 after the motor has been removed from the car? I know the E-68 had dual exhaust, but without having access to the car it came out of hard to determine that. Any external visual clues? BTW, carb and air cleaner are missing too. Sorry, I should add that it is out of a 1975 Road Runner. Thanks!