Rheostat in lower dash of '82 CGT

[TWFAUST at aol.com]

While removing the lower dash to check wiring for my no start   problem, I 
noticed what appears to be rheostat installed through the lower right  of 
the lower dash panel on the wheel side. There is no knob present (missing) on  
the outer side. I was short on time to trace the wiring.
 
In the years that I have used the car, I never noticed it. There are no  
markings. Does anyone else have one of these and know the purpose?
 
Tom