THE ESSENCE: GSD&M, long a leading creative shop, is trying to stay at the forefront of the massive changes sweeping its industry. It's been undergoing what the Austin, Texas, shop describes simply as the Transformation, a bid to sharpen its focus on multidisciplinary strategy and smart business ideas already evident in work for Southwest Airlines. Now what the Omnicom Group agency needs are fresh clients. A stretch of quiet years for new business was broken only in November with the win of BMW of North America's $60 million business. It allows the former Land Rover agency to get back into the category after failing in several high-profile car pitches.