The Single Target Block Signal No. 163 would display either one of the RED (L19R) or GREEN (L19G) lamps that were housed behind its single opaque opening as a train approached. This signal used a 153C Contact that would be placed beneath the track and would be activated by the weight of a passing train.

This single target block signal was produced from 1961 until 1966 and again in 1968 and 1969. Except for the signal head, the No. 163 is similar in function to the No. 353 and both of these signals share a common heritage as descendants of the No. 253 Automatic Block Signal.

Those signals that were sold from 1961 until 1965 came in a ORANGE display box. In 1966 this signal was issued as No. B163 and was housed in a blister pack that was suitable for hanging from a dealers rack. In 1968 they were packaged in an ORANGE box whose end as is illustrated to the right, and in 1969 they came in a plain white box with the information stamped in ink on the end.

There are three variations:

Variation A: Has an unpainted BEIGE base with terminal nuts that are nickel plated. These nuts have a diamond pattern to them unlike the previously issued nuts that have a lined pattern. Produced 1961-1965.

Variation B: Has a distinctively different DARKER BEIGE base that most commonly have brass diamond patterned nuts that are not plated. Produced in 1968 and 1969.

Variation C: Is housed in a blister pack and numbered B163. The value of this variation is based on intact original packaging. Pristine quality of this packaging can command a substantial premium today. Produced in 1966.