Thanks for all the replies,

I am sure they are not part numbers for the three digit ones, however the odd-rod I have has such a long series of numbers and letters that merely a casting number seems unlikely. I have also found that the numbers do not match in any engine I tear down but so far I have found that they are all 3-digit except for this one odd-ball I have.
No, the B18 rods are not needed, thanks. Some other web-site (address escapes me) noted that they were an inferior casting. True? dunno.
I will issue another plea for help if the ones I just got from pick-n-pull don't work (none match but all 3-digit).

Hey, does anyone have strong feelings about mixing and matching rods from one cylinder to another??? They seem to have been stamped with the appropriate number long after casting so I am under the impression that it was for convenience of assembly after select fitting to the piston and pin rather than any other potentially fatal reason.

Mike!