What is this in the car's trunk?

[vs-works]

I was browsing the Coast Classics site and there was a bug for sale. What is that black plastic metal thing in its trunk (I circled it)?

[grandpa pete]

Voltage drop resistor . 6 volt car ; you can tell by the hood prop rod ;
the real early ones had their own top bolt attach point , this one bolts to the hinge bolt .
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63 two fold rag
66 sedan delivery Type 6

http://www.thesamba.com/vw/forum/viewtopic.php?t=569619&highlight=sedan+delivery