Pearson Television executive Bob Oswaks is expected to join Columbia TriStar Television Distribution as head of marketing, sources say. The senior VP of marketing post that Oswaks is expected to take has been vacant since John Moczulski left CTTD about a year ago. Moczulski is now head of marketing for the CBS Station Group. Oswaks currently serves as executive VP of worldwide marketing for Pearson Television. He returned to Los Angeles in fall 1999 after spending more than three years based in London for Pearson. Columbia and Pearson both declined to comment.