On the later cars I've worked on you need to remove the rear wheel, splash shield and then get your arm up behind this "gill" piece. There are 2 or 3 nuts to remove behind it.
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.