Batboard

I am looking to convert a Minitor II to Tone Code Set 8 (A-B, C-B) I have used the information that is provided on the Batlabs Minitor information page. However I am unable to locate the jumper JU3C3. I am told that depending on the revision of the board this jumper may not be present. I am also told that it still is possible to modified the board to due tone set 8. However the person I was talking to could not remember what needed to be done. I believe that the board revision is Revision E. Does anyone know anything about this???