I am trying to figure out if I need to replace the stock harmonic balancer from the 77 440, with a new one, as I replaced the crank with a steel one that is internally balanced. I believe the old one was externally balanced.

 

I am going to assume yes, but I am not sure if it is stamped for cast cranks only.

 

yes, youll need a new balancer, 1 for a steel crank is only about an inch thick, where the cast 1 is 4inches thick and is marked cast crank only. a balancer from a 383 will work. they are the same. alot more 383 motors still in the junk yards.