The block signal was always accompanied by a No. 153C Track Contact. The instruction sheet that was included with this contact was issued for every year this signal was manufactured. First issued during the post war period under the No. 153-45 these instruction sheets are dated 10-45, 4-46 and 12-46. Lionel then changed the number of this sheet to 153C-18 for issues 3-46 and 11-46. This is highly unusual for Lionel to have two different instruction sheets that were available concurrently.
With the issue of 8-47 the number on the instruction sheet changed to No. 153C-22. See the No. 153C page for a detailed listing of these instruction sheets and a picture of the No. 153C-18 instruction sheet.
In April of 1953 Lionel issued a Correction Sheet No. 1312 amending these instructions. The wiring diagram that was on the orignal instructions is illustrated on the back page of Sheet No. 445-55 issued with the No. 445 Switch Tower.
There are three variations:
Variation A: Steel painted SILVER post, screw base lamps in signal head, resistor in base. Base has one, both, or no cast in numbers on the bottom. Nickel plated post finial that is sometimes found painted SILVER. 1945 to 1949 production.
Variation B: Painted steel post, bayonet base lamps in signal head, no resistor in base. No numbers are cast into the bottom of the base. Nickel plated post finial. 1950 to 1956, and 1958-59 production.
Variation C: Identical to Variation B except used an unpainted aluminum post. 1957 production.
Dimensions: 4" x 1-3/4" base. 8-3/4" high