The silver part is the nut that must be unscrewed. That is what the tool I gave you the link to is for.
Edit:
Looking back at this thread, I cannot find the post about the tool. Do a Google Search for "Tool Source". On their web site, use their search feature near the top of the page and type in "antenna". There is a variety of antenna tools. Look at the one on the bottom of the list. You may be able to find such a tool locally at a parts store or a car audio shop.
Frequently I can get by without a special tool, depending on how tight the nut was installed. Try using a pair of long nose pliers. If the tips of the pliers fit the nothes tight enough, use them as a wrench. Insert the tips into the holes on the nut with the pliers standing straight up and try turning the nut off.
Last edited by Big Jim; 09/15/05 11:50 AM.