EXCLUSIVE NEW LISTING FIELDSTON HISTORIC DISTRICT  Classic & Spacious 5-Bd. Stucco & Brick Home on Leafy Cul-de-Sac    This spacious 5-bedroom, 3.5-bath, stucco and brick, Medieval Revival-style house, built in 1929, is set on a quarter acre at the end of a quiet, leafy cul-de-sac. It enjoys a welcoming front dining terrace, a rear patio and grassy front and side yards.    In addition to its 4 bedrooms upstairs (one of which has enough space to be divided to create a 6th bedroom), the house has a large guest bedroom on the main floor with its own fireplace and full bathroom.    The house has decorative archways and is graced by plenty of original woodwork and detail.    Standout features include: a gracious center hall; large living room (30 by 15 ft. with a wood-burning fireplace and a French door to the back patio); handsome formal dining room graced with wainscotting and leaded diamond-paned windows; eat-in kitchen; walk-through butler's pantry; huge master bedroom (24 by 19 ft. with a dramatic 18.5-ft.-high trussed-beam ceiling, oversized northern windows and a Juliet balcony); unfinished walk-out basement with a half bathroom; pull-down steps to a storage attic; central air-conditioning; natural slate roof; multicar private driveway; attached 1-car garage; 0.26-acre lot in landmark district.    Conveniently located for well-known private schools (Horace Mann, Fieldston and Riverdale Country School), the Fieldston community's idyllic Indian Pond, the vast greenery of Van Cortlandt Park, and transportation to Manhattan (including express buses and the No. 1 subway train).