PAC SWI-JACK is what I have in my Jeep along with my 9855 in there. Any adapter will work with the 9855. PAC seems to make pretty decent quality adapters. I think they can be had for around $50 if I'm not mistaken. If you plan on changing the HU at any point, I'd recommend getting the SWI-X. It works with essentially every brand that offers a wired remote control interface. The JACK works with JVC, Alpine, Clarion, Kenwood, and a couple others. It leaves out Sony and Pioneer.