Which Withdrawn has a Previous Class of j69, and a Previous Number(s) smaller than 68532, and a Converted larger than 1959?
CREATE TABLE "great_eastern_section" (
  "number" text,
  "previous_number_s" real,
  "previous_class" text,
  "converted" real,
  "withdrawn" real,
  "disposal" text
);
SELECT MAX("withdrawn") FROM "great_eastern_section" WHERE "previous_class"='j69' AND "previous_number_s"<68532 AND "converted">1959;