After digging around some more it looks like the Kenwood DNX9980HD (and previous models like the DNX9960) use the ASR-1 files as found on the 3790 so I managed to find a copy of them. The following layout now seems to work PERFECT!

My new SD-CARD layout is:

H:\GARMIN
| GMAP3D.IMG
| GMAPDEM.IMG ($)
| GMAPSUPP.IMG
| GMAPTZ.IMG
|
+---\ASR
| 04CNCW00.SRX
| 04CNCW01.ASR
| 04CNCW74.SRX ($)
| 04CNCW75.ASR ($)
| 04CNCW76.ASR ($)
| 04CNCW77.ASR ($)
| 04CNCW78.ASR ($)
|
+---\JCV
| D3060140A.JCV
| D3191130A.JCV ($)
|


The files above marked with "($)" are unneeded/unused by the 9980HD, but I figure it couldn't hurt to have them around. (I know the 9980HD only supports 3D buildings & not 3D topo, so the GMAPDEM.IMG definitely isn't used.) I'm hoping that by leaving the extra files then should I upgrade to a newer model radio (like one with split-screen junction views) then I can use the SD-CARD as-is. Maybe the full structure detailed above is appropriate for ALL current Kenwood models...

So for future reference for Kenwood DNX9980HD (& backwards) owners the major steps involved are:

  1. Obtain latest "City Navigator North America NT ####.## (ALL)" map image.
  2. Unlock using gImgUnlock and rename to GMAPSUPP.IMG.
  3. Obtain ASR-1 files from a Nuvi 3790 (or similar) unit.
  4. Obtain the "large/fullscreen" JCV files.
  5. Merge the above together on a SD-CARD following the folder layout above.


(Now if I could only figure out the secret to Auto-AGREE I'd be really happy!)

THANKS for all you help Neil and maybe by my documenting the major steps here they'll be easier to follow by others.