Three highly successful area stockbrokers who are said to have generated $1.5 million in commissions this year for Smith Barney, Harris Upham & Co. have left the firm to join Drexel Burnham Lambert Inc. Here. u

The brokers, Lenard Feldman, J. Frank Joyce II and Ronald Needelman, worked together at Smith Barney developing a style that stressed investments in fields that many other brokers tend to ignore, although they developed specialties in banking, computer and insurance, respectively.

In fact, during one quarter in 1978, the three men were each ranked in Smith Barney's top 10 sellers. Although not really a team, the three brokers share research information and tips but do not make joint investment decisions.

They recently said that they expect the Dow Jones averages to hit all-time highs during the early part of this decade and that important capital gains will be made in small to medium-sized growth companies.

The men were named to the posts of first vice president-investments by George Fellows, corporate vice president and manager of Drexel Burnham's Washington office.

"Needelman, Joyce and Feldman are welcome additions to our staff," Fellows said. "The trio's experience combined with Drexel Burnham Lambert's acknowledge leadership in corporate equity finance and investment research will be of great benefit to our clientele."