Here is a thread on modifying Nissan wiper arms to fit the Pantera. On the second page there are some measurements given.
Custom wiper arm
I did this mod and would highly recommend utilizing Nissan arms instead of going the OEM route - not only for looks but for area of wiper sweep.
Hope this helps some.
Devin
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.