Circulating Tank Heater?? Coolant heater in 1994 RE Bluebird?

[Mgnmpi]

Flushing the coolant today on my new-to-me 1994 Bluebird TC2000 RE. Been wondering about this thing... I think it is a circulating tank heater, but I'm just not sure. It is connected to the male electrical plug that typically indicates a block heater. It is also plumbed into the coolant system. However, it doesn't get hot. Not when I plug it in, and not even when I brought the engine up to temperature.
Anyone have any info on this little sucker?
Is it indeed a circulating tank heater?
Is there a way to test its' functionality in the summer months?
Why wouldn't it heat up, even when the engine is brought to temperature and all the other heater hoses are hot?
Is there a good replacement out there? I've seen one at Tractors Supply made my Kats, but I'd like an OEM swap if they still exist and this one is broken.
Any info is appreciated!!!

 

[somewhereinusa]

Test for continuity between the two plug blades. It's just a resistance heater so there should be continuity. I've never felt one when engine is up to temp but I would think it should get at least warm. Are the heater valves open? I doubt it it's actually made by Bluebird so any heater that has enough capacity would work.