I love my double D's--so much fun--better (more sensual) than B's. And they win here locally. I can get the '39 down to 4980 pounds. And weight it up to 6505 to pull percentage. It puts out 43 HP on my dyno. And we're at 5600 feet above sea level. I put the low sprockets in and keep the tires at 16.9 X 28. Hanging weights is a problem. I pull 600 pounds up below the rear end with a couple of comealongs.