If you find yourself hanging and taping drywall more than once, and you're not a drywall contractor, you might first want to ask yourself, "why?" Maybe like many remodelers, you find you have to "do it yourself" on smaller jobs and quick repairs. Whatever the reason, if you feel the need for a little "drywall" reading, here's some of what's available. Specifiers, and anyone else looking for comprehensive technical information on drywall products and applications, may need to look no further than the Gypsum Construction Handbook — 90th Anniversary Edition ($15 from U.S. Gypsum Company, P.O. Box 806278, Chicago, IL 60680; 888/874-2450), the oldest reference of its kind, and a long-time international standard for the industry. A quick