State Rep. Mark Siljander won a special election today for the 4th Congressional District seat formerly held by federal Budget Director David A. Stockman.

With 294 of the 305 precincts reporting, the heavily favored Siljander held a lead of 35,293 votes to 13,022 over his Democratic opponent, Cass County Commissioner Johnie Rodebush.

Turnout was light in the first congressional election since President Reagan took office. The largely rural district, comprised of eight southern Michigan counties, has sent only one Democrat to Washington in this century -- riding Franklin D. Roosevelt's coattails in 1932.

Two minor party candidates, Libertarian Bette Erwin and Robert Drenkhahn of the American Independent Party, did not draw a substantial number of votes.

Siljander, 29, was an underdog in the March 24 Republican primary, winning by fewer than 1,000 votes over Stockman's personal choice and former campaign chairman, John Globensky.

Siljander, co-chairman of Reagan's campaign in the 4th District, stressed his longtime support for the president. The only rough spot in his campaign was his tie to the Moral Majority.

Although he had attempted to put distance between himself and the Moral Majority during the general election campaign, Siljander's stands on most issues mirrored those of the conservative religious group.