Dave Mustaine used Jackson Y2KV Dave Mustaine Series until his injury on April 2002.
Before Jackson Y2KV, he used Jackson King V's, which were actually modified to
Here's how he described the process at the time:
"I've been playing Jackson guitars for about 15 years now and my main guitar now is a Jackson Y2KV, which is a little bit different from the King Vs I have. My first Vs were all custom ordered because they didn't make a 24-fret V, except as a special order and my original guitars all had Kahler bridges. One of the modifications I've made on the Y2KV is that I got rid of the Kahler and put a stop tailpiece on the new model. Another change is in the construction and body design. The King V has sharp points, but the Y2KV has rounded ends and the wood used is a little bit softer, so it has a smoother sound and it resonates better. I don't dig the harder woods because I think the tone is too brittle. I think the wood is mahogany and the fingerboard is rosewood or ebony. I have a couple of korina ones. I believe my doubleneck is made of korina. We've also made some changes to the pitch of the headstock, so that there's less tension at the nut."
Since Jackson Y2KVs are discontinued, they are considered collectible. Online auctions are the best places to find Y2KVs.
For Y2KV eBay auctions, follow the link.