What part numbers will I need to purchase from Harley to get XM radio to work with my Harmon Kardon head unit and still be able to use handle bar controls ?
You need the oem xm module with antenna and the ultra overlay harness (https://www.harley-davidson.com/store/boom%21-audio-system-wiring-harness-pa-08-7016906--1).
Welcome to the forum.
I don't think you need anything for just listening because the Sirius XM radio will broadcast to your Harmon Kardon FM radio (at 88.1 IIRC) if you mount the Sirius radio on the bike too. You will have sound control because it shows up the same as a radio station broadcast but to change stations you have to switch them on the Sirius unit. AFAIK to get full control on your radio head unit it must be Sirius Satellite capable (have it's own sat radio inside) and you then have to buy a separate subscription to the bike radio.
If you have favorites set up on your existing Sirius radio channel changing is not hard (if you aren't wearing gloves and riding in heavy traffic).
https://shop.siriusxm.com/installation/sirius-audio-optimizations.html
Added later:
Coyoye posted while I was typing and he knows this stuff so there's the answer to doing it all in.
The OP will need an OEM XM module to get what he said he wanted. The harness is required as there is no FM modulator in the OEM module.
ebay has used modules 76165-06A, would this work and I change the preset channels on the unit since I only listen to a couple XM channels .
Yeah that's the one. Make sure you get an antenna for it too. The overlay harness will plug into the open connector on your HK radio. One connector will plug into your main harness. One connector will plug into the XM module. The others are unused. When I do this install, I take time to remove the other connectors/wires from the overlay harness. It's not required but makes it much easier to deal with the added harness inside the fairing.
I'm almost sure I have a new takeout overlay harness. Since we moved, I have no idea where it might be. I can take a look tomorrow and see it it's easy to find. May also be some takeoffs on EBAY
Appreciate , let me know !!