Once the threaded nut with the square head is removed, the temp sender bulb should lift out. Be careful not to flatten or break the capillary tube- - - -it's not a solid piece, it has a tiny hole in it that goes to the dash gauge. Penetrating oil and carefully wiggling it with pliers usually loosens it up.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!