I believe the year De Tomaso was the featured marque was 1997. Tom McDowell runs things a bit differently. The Concorso under Tom celebrates all anniversaries occurring during any given year. His stage shows are therefore quite a bit longer and more comprehensive than they were under previous organizers. And they move quickly to fit everything in.
The fiftieth anniversary was celebrated in 2009. The Concorso was following up on the disappointing 2008 showing at the Marina air port, the last year the event was organized by Wadsworth. For 2009 there was a new organizer, Tom McDowell; and a new venue, the Laguna Seca golf course. He did a good job for his first showing, including remembering the 50th anniversary of the marque.
The Concorso had a special De Tomaso display which included the Elvis Presley Pantera from the Peterson Museum. They made sure the marque was well represented by making special invitations to owners of De Tomaso cars other than Panteras, such as Tom Galli's Mangusta, Greg Sullivan's Longchamp, and a light blue Vallelunga (I believe owned by Franco Manitti). Debbie & I presented a special tee-shirt ... "De Tomaso circa 1959" .... to each exhibitor. I believe Tom Tjaarda gave a discourse on stage of his memories of working with Alessandro De Tomaso.
That was the first year Pantera International gave gifts to exhibitors, a tradition we've perpetuated since then. I've worked steadily at earning the respect of the event organizer and judges ... I believe that culminated with a Mangusta being awarded best of show two years ago ... a first for a De Tomaso.
Don Emas won Pantera International's best of show award in 2009 ... I expect to see him back there in 2019 ... right Don?!? 
