IF YOU'RE THINKING OF LIVING IN: LEVITTOWN

-SIX years after the Levitt

house appeared in the potato fields

of Nassau County as an innovative refuge for returning World War II veterans and their families, Levittown is again serving as a source of homes for young married couples looking for affordable housing and a pleasant community in which to begin raising a family.

As retired homeowners move out, the new young families are moving in, continuing the transformation of Levittown. ''It's a perfect starter house,'' said Barbara Tufano, who recently bought a six- room ''handyman's special'' on Hunter Lane. She said her husband, Carmine, a carpenter, had added four more rooms and ''expects the house to last another 30 years.''

''The Levitt house is a good buy,'' she said. ''It's well laid out and you can do so much with them.'' She noted that she and her husband had recently bought two other Levittown houses as income properties for themselves and their eight- month-old son, Carmine Jr.

Leslie Campbell, who lives with her husband and two young children on Elm Tree Lane, said that to find similar prices they would have had to move to Suffolk County. ''And since my husband works at two jobs near Levittown, and the price was right, we bought here,'' she added. ''If we lived in Suffolk, we'd never see him.''

Many of the Levitt Cape Cods and modified ranch homes have been remodelled, reshingled or expanded, as the community continues to confound those who nearly four decades ago predicted Levittown was a future slum.

The first residents paid $65 a month rent with an option to buy for $6,990 (no down payment for veterans). By the time the last new ''ranch'' was sold on Tardy Lane in November 1951, the basic home built by William J. Levitt cost $9,500. Now homes cost $65,000 to $95,000.

The first 300 families moved into the uniform, four-room Cape Cod houses in September 1947. Nearly 17,500 houses were constructed. The original Levitt house was 750 square feet, with a living room, two bedrooms, a kitchen, bathroom and ''expansion'' attic, according to John Pergola, one of the original Cape Cod residents who has operated a real-estate agency in Levittown for 25 years.

He noted that many of the homes have been doubled in size as owners raised raised their roofs, added dormers and pushed out their walls to include new bedrooms, dens, sunrooms and garages.

The initial low cost of the Levitt houses was made possible by mass construction techniques as innovative in their time as those for the Model T Ford assembly line in its time. More than 30 houses were going up each day at the peak of production - basically of the same design, but with some variations.

The Cape Cods were offered in three models, and the ranches in five variations. But in each, the floor plan was the same. The construction was deliberately designed so that additions or other alterations could be made.

The developer encouraged change by placing the homes at different distances from the street and at different angles on each plot, which averaged 60 by 100 feet.

To facilitate development as a garden community, ornamental trees and shrubs, as well as four fruit trees, went with each house. There were also nine community swimming pools, half a dozen ''village greens'' that included a few shops, such as groceries and coin laundries, and more than 116 parklike playfields.

The community sprawls across some 7.3 square miles in an unincorporated area almost entirely within the Town of Hempstead, with a tiny bulge in the Town of Oyster Bay.

For many of its 65,000 residents, Levittown is still a stepping stone, still the first house in the suburbs, a factor demonstrated by its annual turnover rate of around 10 percent.

Situated just south of the center of Long Island in Nassau County, Levittown identifies with neither the South nor the North Shores of the Island. It sees itself as a mid-island community, with concerns that reflect those of the county in general.

Levittown residents have long led the battle to hold down property-tax rates on the Island, and have dealt with such problems as providing working parents with day-care centers at neighborhood schools, and creating programs for the growing population of elderly.

This graying of the population in Levittown has been the most recent concern of officials worried about a declining school population. However, they note that the drop in interest rates over the last year has enabled some new young couples to move in.

During the past several months the shrinking school enrollment led Levittown officials to close a high school and convert it into a district, adult- and special-education headquarters.

Levittown's school system began in a three-room country schoolhouse in 1947. By the 1960's it was one of the largest in the state, with more than 16,000 students and a budget of $9 million. Total enrollment this year was 8,000 students. The current budget is $43.2 million, for the operation of two high schools, two middle schools and six elementary schools.

THIS year's graduating class will be

700 students, 83 percent of whom are

expected to go on to higher education, according to Gerald Lauber, superintendent of schools.

He noted that test scores in the district had ''gone up dramatically'' as the result of a new reading program that matches the reading level of each student with a variety of textbooks.

As for changes in student enrollment, Mr. Lauber observed: ''We are still losing about 300 students a year from the system, but we expect that to stabilize as home sales increase. We are looking forward to a rebirth of the school district.''

The current school-tax rate is $25.82 per $100 of assessed valuation. The school tax on an average $70,000 Levittown house would be $1,291.25. When additional county, town and fire district taxes are added, the total current tax bill for the same single-family house is $2,442.95.

The Nassau County police say their biggest problem in Levittown has been simple criminal mischief and residential burglaries, primarily by youths, but that both had been decreasing with the aging of the community's population.

Hempstead Turnpike, which runs east- west through the center of Levittown, is the main street for business and entertainment. The Roosevelt Shopping Center, the largest mall on the Island, is in nearby Uniondale.

There are six Protestant churches in Levittown, along with two Roman Catholic churches, one of which is undergoing a $1.8 million renovation, and two Jewish congregations, reformed and orthodox.

Fred Neist is chairman of the Levittown-Island Trees Youth Council, which provides a program of athletics, art and music for 14,000 children. He moved to Levittown 33 years ago and three of his five children also now own homes in Levittown and are raising their families there.

''We find many of our children coming back to town as professionals - teachers, lawyers, doctors - and setting up business here,'' Mr. Neist said, ''and that pleases us.''

Although the Levitt organization built Levittown, complete with sewers and roads, part of its infrastructure is now in the process of being replaced. New sewer and major repaving projects are under way.

Residents who make the one-hour commute to New York City have a choice of traveling several miles north to the Long Island Rail Road Station in Hicksville, or several miles south to the Merrick, Bellmore or Wantagh stations.

On either line from those points, the monthly commutation ticket is $91, or $28.25 for a weekly commutation ticket. One way to Manhattan is $4.15. Off-peak, round trip is $6.25.

Bus service to the railroad stations and along the major roads - Hempstead Turnpike, Newbridge Road, Jerusalem Avenue and Hicksville Road - is provided by the Metropolitan Suburban Bus Authority.

The bus fare within Nassau County is 75 cents one-way. A special ''Uniticket,'' or combination bus and train ticket, is also available. For an additional fee of $15 dollars a month, railroad ticket agents add a M.S.B.A. sticker to the L.I.R.R. commutation ticket.

Motorists can reach Levittown by several major routes: the Long Island Expressway to Exit 41, then south on Route 107; Northern State Parkway to Exit 33, south on Wantagh Parkway, then east on Hempstead Turnpike, or Southern State Parkway to Exit 27, north on Wantagh Parkway, then east on Hempstead Turnpike.

Levittown's growing number of elderly residents has led to new pressure to provide property-tax relief and other assistance.

After a special public hearing on the measure, the Levittown Union Free School District Board of Education recently raised by $3,000, to $13,500, the maximum income that elderly residents can make and still qualify for some relief from property taxes. The change created a sliding scale of exemptions, from 50 percent for incomes up to $10,500 to 20 percent for incomes up to the new maximum.

''This relief is available to the elderly in all districts in Nassau County,'' said Gerald Lauber, the superintendent of schools. ''But it's up to each district to act on it.''

Elderly residents can also take vocational classes in such subjects as TV repair and house construction at the old Levittown Memorial High School, Mr. Lauber said.

''They are also invited to come to the school for breakfast and lunch,'' he added. The food is prepared by cooking-class students; the elderly pay 75 cents for breakfast and $1.25 for lunch.