Temperature gauge assembly

[First time restorer]

I am replacing the temperature gauge assembly on my 1939 Ford and am having trouble getting the old nut off the head. I’ve tried soaking it with master blaster but it won’t budge.
Any ideas?

 

[VeryTangled]

Hi, I have '35 and '36 cars, but my hint is if the dash is in the car, remove the speedometer to improve access to the gauges mounted beside it.

 

[Jacques1960]

Red wrench, i.e., quick touch with a brazing / pencil torch ?

 

[TerryOH]

Use a line wrench, and a bit of heat helps.