Forged crank really a Cast crank

Dropped my 340 stuff off at Armstrongs engine rebuilders a few weeks ago...block to be bored, crank grind and balance, etc.
I had just taken the word of the previous owner it was a forged crank...after all ,it didnt have the cast crank balancer or weights on the flywheel
Armstrongs calls yesterday and says its actually a cast crank and its been running out of balance 80 grams!
WOW! how the hell did the thing stay together for 10+ years????
anyway, they are going to internally balance it...but...WOW!