I often hear from new ES owners that did not have the jack adapter, PN 3458, and I was unable to secure any.  I was able to find a manufacturer to make them from a 3D scan.  The original ones seemed to be aluminum, but these are steel.  I am going to make a group order NLT April 10th, 2024.  If you would like one, let me know (edit: use email or PM links in profile) and I will add you to the list.  The turnaround was 3 weeks.  They are $200 each.