Might have to take apart the interior but I cant think of any reason engine removal would be necessary.
The easiest way to do the job of course is to take the car to the vendor and just get out the check book of course.
Luckly in SoCal the heater is not very important to enjoying the car.
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.