The long: Diesel engines join elegant antiques and serene gardens at Winterthur on Saturday, when Henry Francis du Pont's turn-of-the-20th-century, 979-acre Delaware estate has a day of fire trucks, backhoes, cranes and a mechanical dairy cow.

The short: Du Pont-land meets Diggerland.

The demo: If they're big enough to be hoisted into the seat of a John Deere . . .

Saturday only: Now in its fourth year, Truck and Tractor Day lets kids put out a fake fire, milk a faux cow, climb ropes, hop into immobile vehicles galore and take a moving hayride (and the ever-present Garden Tram) around the grounds, do crafts, eat hot dogs and Woodside Farm Creamery ice cream, take home plastic helmets.

Friday or Sunday bonus: Admission is always good for two consecutive days.

Timed tour: Free, ticketed guided tour takes guests through entertaining spaces of the manse, done up in gilded century-ago style. Strollers permitted. Touching is not.

In the museum: Two Tiffany-themed exhibitions: one of the painted glass, another with gleaming wares from the stores; plus Pennsylvania German Fraktur folk art and antiques.

Enchanted Woods: Kids' favorite garden portion features fairy cottage, troll bridge, magic mushroom circle.

Moment to yourself: Outside the Downton Abbey-like delights, a 60-acre garden has a reflecting pool where begonias bloom, a bog boasts blue clematis and the Sycamore Hill kousa dogwood bear raspberry-like fruit.

The basics: 5015 Kennett Pike (Route 52), Winterthur, Del., 10 a.m. to 4 p.m. Saturday, rain or shine, $20 adult, $18 senior/student, $5 ages 2 to 11, free under 2, 800-448-3883, winterthur.org.

Lauren McCutcheon is a Daily News features reporter who wonders what kids obsessed over before trucks and tractors were invented. Horses, perhaps?