I have no idea what's going on with these discs. This is a confusing subject.
The MDX came with ver. 4.13D and only had the DVD in the player under the passenger seat. NO other disc with the records or manual.
In January, I paid $185 for ver. 4.81, which included 2 discs, a software update and a map update, now selling at eBay here
It made a huge difference in Lexington KY where I was visiting my dad. The entire southeast area of Lexington is shown as vacant land on the ver. 4.13. The 4.81 has all the new streets and connector boulevards that were built between 2005 and 2009.
Last month, I paid $99 for ver. 4.92, a single disc, which seems to be a map update only, a point I did not realize prior to purchase. I still think it was a waste.
I noticed on the NAVTEQ website that a ver. 4.92 two disc set is selling for the customary $185, which must be a software disc and a map disc.
The packaging seems to indicate that each disc is year model specific.
It will be awhile before I do this update again.