What date did the T328 that entered service on 18 June 1956 re-enter service?
CREATE TABLE "locomotives" (
  "locomotive" text,
  "pre_conversion" text,
  "entered_service_t" text,
  "re_entered_service_p" text,
  "owner" text
);
SELECT "re_entered_service_p" FROM "locomotives" WHERE "entered_service_t"='18 june 1956' AND "pre_conversion"='t328';