Allen's right, you on't want to put your sensor back in the stock location, If the water level drops below the sensor your reading would be of the air temp rather than the actual coolant temp. which could be a significant difference.
Put it in the block.
Hopefully you won't have as much trouble as Allen did getting the plug out.
Good luck
Gary #06984
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.