I've had three date codes from Contaucreek for both CAV and Bryce equipment:
CS43195 spec 10/2/30 1941? 10/2
CAV LH - Pump dates to October 1941
372 16/2/31 1981 16/2
Bryce TY - Pump dates to June 1981
495661R7 1957 6/1
CAV FY - Pump dates to May 1957
I checked the 1ZHR today, and that has date code VA, which we make to be August 1959, against a selling date in 1964, so presumably the pump or engine was in stock for a while.
The 1YB has a Ruston labelled pump with no date code on it.
Peter