Briefly :

Resales of single-family homes in Ventura County declined nearly 4% in December from November, the California Assn. of Realtors reports. December’s sales activity was off a steep 22% from a year earlier. And median resale prices in December were $200,650, down 2% from December, 1993. . . . Ducommun Corp., an L.A. producer of aerospace components and assemblies, acquired 3dbm Inc., a Camarillo maker of communications systems for military and commercial customers, for $5.8 million in cash and notes. . . . O’Donnell Property Services Co., an Irvine concern, has been retained to manage nine Ventura County industrial properties owned by Oxnard-based TOLD Corp. TOLD is headed by Jack Gilbert, who created the landmark Channel Islands Business Center in Oxnard, then lost much of it during the real-estate downturn to a unit of Wells Fargo Bank. The nine projects to be managed by O’Donnell total 900,000 square feet.