I am missing the metal box to house the wires underneath the washing mashine, any suggestions?
Here are your parts
Body parts replacement parts for General Electric HDA2100F01WW Dishwasher | AppliancePartsPros.com
See Items 741 and 743 in Section 2.
Or you could just mount an electrical box and get a solid face plate for it.
Or and I am not recommending this as it goes against the electrical code, not bother with the box as long as the wires go through a strain relief and use approved wire nuts.