Try driving a flat blade screwdriver in the slot to open up the splines. You also might have to persuade the joint off the splines with a mallet or brass drift.
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.