I spoke with Happi jac yesterday. They told me the old style motors are obsolete and no longer being produced. They also told me the new motors will not work on my 4800 jacks but e trailer says they will but with the new control board. I tried to purchase a couple of old style motors but couldn’t find them anywhere.  If and when one of my motors fail I hope to be able to buy a new board and new motors but use my existing jacks. I also need to check the clearance of the cab over to the new motor. Happi jac says you need 9 1/2 “ clearance from top of the jack. Good luck to us all