The Oakwood Center office building in Fairfax is nearly complete, according to the Washington office of Turner Construction Co., the general contracting firm that began the construction 10 months ago.

The seven-story building has 135,000 square feet of office space and a 36,000-square-foot garage.

The building is being developed by the Turner-Harwood Joint Venture. It is scheduled to be occupied in October.

Other developments in local commercial realty:

* The Equitable Life Building at 8300 Greensboro Dr. in McLean has been sold to RREEF Funds of Chicago. The 295,000-square-foot building was previously owned by Equitable Life Insurance Co. Tenants include the life insurance company's corporate headquarters, IBM, MCI and Dynalectric.

* John Hanson Savings and Loan recently expanded its Lanham office by 1,000 square feet. The office is located in the Giant Food store at 7546 Annapolis Road.

* Moulding and Millwork Co. Inc. has leased 30,000 square feet of space at 3101 Washington Blvd. in Baltimore.

* At Flint Hill Office Park in Fairfax, Mortgage Guaranty Insurance Corp. has leased over 4,400 square feet and Crawford & Co., an insurance firm, leased over 4,000 square feet. The building is located at the intersection of routes 66 and 123.

* National Data Corp., a computer support and time-sharing service company, has leased 10,000 square feet at 1300 N. 17th St. in Arlington. The aggregate rental of the lease is about $2 million.

* TDX, a private telephone company, has leased 10,000 square feet for a new switch assembly facility at 4215 Walney Rd. in Chantilly.

* Steelcase Inc., a designer and manufacturer of office furniture, has leased 6,000 square feet of space in the Washington Design Center, currently under construction at Fourth and D streets SW. Decorators Walk, an office design company with headquarters in Planview, N.Y., will open a showroom in 9,000 square feet of space it recently leased at the center.

* J.R.'s Goodtimes, a food service company, is developing a 216-acre recreational park near Leesburg. The facility, which will be called Festival Lakes, will offer swimming, horseback riding, boating and dining.