The 30-year-old Shiley Duke and Regina apartment complexes in Alexandria are being rehabilitated with $77 million in federally subsidized funds. When completed, the complexes have more than 2,000 apartments, including some for low-income, rent-subsidized tenants.

One of the largest federally backed apartment rehabilitations, the project is a joint venture of Baltimore developer Morton Sarubin and the National Housing Partnership. The builder is Bush Consruction Corp. of Norfolk.

Scheduled for completion in mid 1982, the $97 million project, located between Duke Street and Shirley Highway, is expected to house 5,000 persons in four villages with 200 buildings. The units have been vacant for several years. Rents are expected to range from $300 to $500 a month. The project's West End Shopping Center is also scheduled for rehabilitation.

Sarubin, who has handled rehab projects in Baltimore, began efforts to buy the Shirley Duke complex in 1978 after it went into bankruptcy. Recently, the Virginia Housing Development Authority approved a $72 million construction loan financed by the sale of tax-exempt bonds.

Then the Department of Housing and Urban Development provided a guarantee of the long-term financing under its Section 221(d)(4) below-market interest program in tandem with the Government National Mortgage Association. Concord Mortgage Corp.of Silver Spring processed the loans. aSettlement proceedings were completed last week.

The architect is Nelson-Salabes Inc. of Towson, Md., and Holland and Associates of Alexandria is handling the engineering work.

After two years of negotiaions, Sarubin purchased the Shirley Duke apartments from Prudential Life Insurance Co. and the Regina apartments from Morgan Guaranty Bank.