Our Navy RBB and RBC receivers use a 6-8B current regulating tube to maintain a stable oscillator.
These are getting rare and expensive to find.
One solution offered is a 20 ohm 10 watt resistor in a tube base to replace the tube.
Another is to make a simple voltage regulator circuit in a tube base.
Since the original tube was a current regulating device, would a resistor or voltage regulator do the same job?

 

The problem with a simple resistor is that the current varies linearly with the voltage differential.

You have not mentioned what is the supply voltage, but this could be very likely duplicated with a solid state circuit, consisting of a Mosfet and suitable control circuitry.
EDIT: I read about these tubes. It is a resistor with a positive temperature coefficient. That would suggest a PTC thermistor, but the thermistors usually have a very sharp transfer characteristic, while the tube's datasheet indicates a very wide flat area.
So the solid state solution may be the best option.

 

They do regulate current not voltage and can work equally well with AC or DC. Making a DC constant current source is not difficult and with a bridge rectifier this could handle AC too.

The Amperite automatic current regulator is a reliable current regulating device, which
can maintain a constant current in a circuit over a very wide range of input voltages. It
consists of a resistance wire with a positive temperature coefficient of resistance,
hermetically sealed in a bulb containing hydrogen or helium gas. The resistance of this
element will automatically increase or decrease in accordance with the change of
temperature in the unit to maintain a very accurate current level.