It was probably a feasabilty exercise to see how the vehicle handled / performed with drive train at the rear. The adjustable suspension and added length could be a clue. There was no point in creating the complete piece of equipment if problems were found in the basic vehicle. It could be as someone has said, that it might have been aimed at something like the S tank, or possibly a lightweight CET. The CET has suspension locks when operating the bucket, you do not need the hull bobbing up and down when operating, those rams may have been for that purpose. As Mike says, at Chertsey, they dreamed up all sorts of ideas.