Harmonic balancer

I am looking for some help and guidance. I am working on my 1972 Plymouth Scamp. It originally came with a 318, it now has a 360 block from 1976 assuming I read the numbers correctly. This is the balancer that I took off this morning. I am trying to figure out if this is an internal or external balanced dampner? I have read that all 360's are external balanced. I have a 727 3 speed transmission, the previous owner did not know anything about the car.

Balancer Front Side.jpg

Balancer back side.jpg