"The 3 wire feed was required to be on a 4 wire. Was a subfed panel."
The old dryer is of no consequence. It is only a "3-wire dryer" because that is what cord was put on it.
The circuit determines what cord to put on.
Most dryers I have seen have had a green wire run from the grounding screw into the wiring harness where it was bonded to the neutral.
I just remove the wire, cut off the fork terminal and cap off the wire securely.
Then the cord gets wired typically with the green from the cord to the ground screw on the chassis.
