Steve....Hard to tell, but it looks to be a genuine guard , from the rolled edge at the chain indent, rather than a generic guard modified to fit. Then again, the flair is missing under the rear number plate, the rear section has a bolted rather than riveted mounting and I cannot see a central rib or hinge. I have seen later machines without the rib, but don't know if or when the guard changed.
Someone will be along with the answer.
Swarfy.
