1978 400 crank question.

You can see a visual difference of a forged or cast crank easily.the casting line that goes all the way down the crank OS the tell tail. Cast will have a very thin line(width of a to.her nail or so) where the casting is put together. A forged has a wide mark with grind marks on it usually about a 1/4 Inch or better in width. Also a forged crank looks rough on the counter weights edges. The casting looks cut almost perfectly. Not balance can tell you which one it really is. Only the crank itself.

Hope this is helpful to you. Also I've got a 76 and its cast. So to get one even newer is pretty much impossible to find.