Here are a couple of images of a CTL 4031 B and CTL 4031 C together.   
 
In FWC-02, Carrier, Windsor Mark 1*, Illustrated Spare Parts List, the correct nomenclature for the tool in your possession is: 
 
CTL 4031 C, Wrench - brake adjuster and axle drain plug.
		 
		
		
		
			
		
		
		
		
		
		
		
		
	
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