Young Americans for Freedom, an ultraconservative Republican group, is purchasing stock in U.S. corporations to force votes at shareholder meetings on ending trade with communist countries.

General Electric, Du Pont and Standard Oil of Ohio are the initial targets, according to Peter Flaherty, director of projects for YAF.

All the companies have asked stockholders in proxy statements to vote against the YAF proposals.

"YAF has had a Stop Red Trade project for 16 or 17 years -- almost since our inception," says Flaherty. "In the past, individual members have used their stock at annual meetings. This is the first year we're going as an organization."

The tactic of dissident shareholders using a few shares of stock as a wedge to force companies to change or adopt specific policies has blossomed in the past 10 years.

"Liberals have sort of always taken a lead on stockholder options, but conservatives are getting more and more involved," says Flaherty.

In its statement to stockholders asking for their proxies, the $80,000-member YAF says U.S. business dealings provide communist nations with the technology and capital they need for their expansionist military policies.

The three companies singled out by the YAF report their trade with communist countries is insignificant, with GE saying its business with them amounted to less than a quarter of 1 percent of sales last year.

Overall U.S. exports to communist countries totaled about $7.6 billion in 1980.

Two of the countries with which the YAF would end trade are not considered communist by the State Department. They are Yogoslavia and Macao, the Portuguese colony near Hong Kong.