ARP rod bolt ID

[1972ho]

Does anyone know when arp started marking their 8740 and 2000 rod bolts with a id. number ie (arp 8740)and arp 2000.The reason I ask is I have a set of rods bolts with arp arp written on them and not arp 2000 or arp 8740 I just want to try and figure out how old the rods and bolts are.Thanks

[pdq67]

Drop a $Buck or two and call ARP.

pdq67