I don't think they've changed the drive unit since Noah installed the first one when he upgraded to wheel steering. It seems the AH4000 has the control head, computer, and flux compass all in one unit, but the connection to the drive is just two leads, correct? The new connection to the drive motor is a two pin plug with a twist lock. If this is what your drive has than it is probably a drop in fix. If not, you might have to get a new power cable for the new drive. Other than that I can't see any issues with getting a newer drive unit.