Cool. Maybe mine has a forged crank too.
I think its safe to say that most would have a cast crank and if a fella gets lucky, he may find one with forged steel crank. Only way to know for sure is to open it up and look.
Cast.
If I recall, 400's only came with cast cranks. There may have been some early 72's that had forged cranks, but Im not sure.
Being a 78, it would have a cast crank from the factory.