A903-- clutch interlock needed?

[wrock]

I have a 68 Dart, and want to replace the A903 with an earlier one, from a 66 A body. The '66 trans does not have the pin to attach the shift lockout mechanism (that does not allow the car to be shifted unless the clutch is disengaged). Is this lockout required, or is it just a bit of later-A idiot proofing?

Any thoughts are appreciated.

Thanks.
Bill