[oletrucks] What good is that little spring on the upper door hinge good

[SurfDudeSC@aol.com]

So I'm rebuilding my door hinges on my 57 GMC 1/2 ton and notice a spring 
about 1/2" diameter and 2 1/2" long.  I see the one "hook" on the hinge where 
one end of the spring hooks but where in the world does the other end hook.  
Nothing in my service manual and nothing in the factory assembly manual shows 
it.  So the question is where does the other end hook and what good is it?  
Any info appreciated.  David
oletrucks is devoted to Chevy and GM trucks built between 1941 and 1959