From the Wikipedia article, with emphasis added:

All 1980 Eagles came standard with a permanent four-wheel-drive system that employed a New Process 119 transfer case that had a viscous fluid coupling that allowed the four-wheel-drive system to operate on wet or dry pavement without causing undue suspension and drivetrain wear.

Why didn't you TSI it?

Michael Barry
Technician
Quick Stop Smog & More
Sacramento, California, USA