Anyone know anything about flathead 6 engines?

I have a couple of '40's Mopars ('47 plym convert and '47 Dodge D25c - the Canadian export one) both run the flathead. I did spin a bearing on # 5 in the convert many years back and that knock could be a bearing knock. They are pretty hard to kill though so unless it's very pronounced you may get away with it for some time. On the other hand when you can hear something wrong with any engine it does tend to make you nervous eh?
Why don't you post a pic of it?
Regards
Gary