Kevin,
I removed this Lucas headlight from a carrier in northern Manitoba some years back and by the picture you can see what Rob was talking about,the headlight on the right is a Canadian style and the left is the Lucas style.I would imagine that if it was mounted on the carrier that it would be original to it.I can't see using the Lucas headlight style as a replacement for a Canadian style.Unfortunately there is no way of identifying what serial number range this carrier was built as all the armour is cut off but (correct me if I am wrong) is a Canadian built Mk 1 design.
I also was looking in my manual and found the diagram showing the 2 types of headlight designs but found no reference to when the changeover took place.Anyone else have an idea?
Derk.