My 2010 Coachmen is on a 2008 E450 chassis. 07 through 10 you may find many unusual parings as manufacturers had ordered cut-aways and the market tanked. In my case it's really convoluted as Forest River bought Coachmen and built the 2010 model with some visible, and invisible construction changes, and used one of the unused chassis from 08. Major impact is 1/3 of the tire life has already passed by the time it's delivered.
Couple of years ago I looked at a really neat looking Fleetwood Quest on a Sprinter. Opposing double slides. Research turned out that Fleetwood had made a special run of this design using leftover materials in the warehouse from 07. NO TWO WERE ALIKE. After using up the surplus components they never made that model again.
For registration purposes the date of the motor home build is used. You need to contact Ford to get your warranty start date adjusted to date of purchase.
Lucked out once when Camping World had a mis-registered Winnie (08 registered as an 07) and priced it as an 07. Not all was gold however, as there was a major engine change, but Winnie engineers didn't upgrade the frame extensions so I lost 1500 pounds of tow capacity.