Several key executive changes were announced at H. L. Rust Co. following the real estate, mortgage banking and insurance company's recent merger with Jackson-Cross Co., of Philadelphia and Wilmington.

H. T. Beuermann, president since 1974, has been named chairman of the board of Rust Co., and Clement H. Gimbert, former vice president of Peoples Life Insurance Co. of Washington, will become president of H.L. Rust on Aug. 22.

Former chairman Lloyd B. Wilson Jr. will remain with the firm as vice president in an advisory capacity. Vice president William S. Green, as well as other officers, also will remain with the company.

In addition, Beuermann and Gimbert were elected to the board of directors of Jackson-Cross, while Charles F. Seymour, president and chief executive of Jackson-Cross, and J. Richard Jones, president of Jackson-Cross-Philadelphia, were voted to the board of Rust.

Jackson-Cross, with 100 employes, is about twice as large as Rust and is engaged primarily in leasing and real estate appraisal.

"The combined affiliation will have gross annual sales of about $10 to $12 million," said Beuermann."It's a great marriage."

Beuermann has been with Rust for 34 years. He was named senior vice president in 1971.