It's not missing, it never existed from the factory. The covers you see are aftermarket and should be used as show only since they block the cooling vent of the clutch.
PANTERA INTERNATIONAL
A DE TOMASO CAR CLUB
Presents the De Tomaso Forums
The On-Line Meeting Place for De Tomaso Owners and Enthusiasts From Around the World
Clicking on the banner will take you to the sponsor's website.