instrumentation on the title song of "The Last Waltz"

I'm trying to find out what the instrument is that Mr. Robertson was
playing on the title song of "The Last Waltz" at the end of the movie?
A double necked instrument if I saw right. Guessing something South
American.

If anyone should see this that knows, I would apprciate and email at
john@[EMAIL PROTECTED]
 put something about the Last Waltz in the subject line of the
email so I can pick it out from the spam.

Thanks.