OK, the quoted web address needs be the actual web address to your build thread. Here's the code for your signature:
URL="http://67-72chevytrucks.com/vboard/showthread.php?t=539403"]
1977 Chevy C10 SharkBite[/URL]
If you want to copy this straight into your signature, you'll need to add the bracket before the URL (like this: [URL ) in your code and change the red text to whatever you want it to say. Otherwise, click the link button in your signature editor and paste your build thread web address into the pop-up. Once the code is in your edit box, you can change the web address (only the non-quoted web address) to read whatever you want, like the red text above. If you delete anything between the 1st set of brackets, from URL to the last quotation mark around the 1st web address; or the last /URL and it's brackets, it wont work properly.
This is what it will look like:
1977 Chevy C10 SharkBite or
SharkBite just by changing the text in red.
Let me know if you need more help.