Students at Taft Elementary School in Santa Ana got a preview Monday of the annual Toys on Parade, which will be held Dec. 6 and which city officials hope will attract 150,000 viewers this year. For the third edition of the parade, which features the West Coast's only procession of balloon-type floats, the city has arranged for the Marine Corps' Toys for Tots program to be the official charity. Parade watchers are asked to bring a toy to the event and drop it off with one of 36 Marines stationed along the downtown parade route. In addition, U.S. Postal Service employees will work the route, as they did last year, collecting children's letters to Santa Claus. Once again, said parade coordinator Elise Swanson, every letter will be answered, although she stressed that each one must be accompanied by a stamped, self-addressed envelope. Some floats were unveiled at a press conference Monday. Swanson said the 1986 lineup includes 7 balloons, 8 floats, 9 mini-floats, 10 "inflation floats" and 15 bands from as far away as Boise and San Jose. A number of celebrities will ride in the parade and the grand marshals are Falcon Crest stars Lorenzo Lamas and Ana Alicia. The city has allocated $215,000 for the parade this year; it will be televised on Channels 9 and 34.