Crank pulley: what's the number on the balancing rim

[cinquecento]

Relating to an interesting thread on crank pulleys and trigger wheels ( see http://www.pistonheads.com/gassing/topic.asp?h=0&a... ), BB posted some pictures of his crank pulley assembly with a number stamped on the balancing rim. In his picture the number stamped is 1317. I have 1971 stamped on mine.

Any ideas what the number means?

[steve-V8s]

I think it is a balancing number, In the event that you need a new pulley or damper Power can make up a new one based on this number ( so I am told )