Does it have grey or black/ charcoal colored lower front paint and chassis paint? Grey was the earlier paint/ charcoal/black is the newer color. Date of manufacture is different from date of sale. They can mark the sales receipt as a 2010, 2011 or 2009 depending on when bought, but actual production year is a function of serial number. Not that it makes any real difference, but some don't want to buy for instance something produced in 2008 which came on the lot in 2009 and would be sold as new in 2011. For all intents and purposes date of first retail sale is the year of sale of the tractor in question. BUT if resale time comes along and one can't produce original paperwork then it could be an issue for a potential buyer.
I've had a both a DK35/se/hst and now a DK40se/hst. Both are were great tractors but the 40 is definitely the sweet spot for the compact line that Kioti sells. I have a Kioti KB2485 which is awesome for digging. I had it for my DK35 and moved it onto my DK40 and it works well in both applications. The 401 loader is great too. It has about 1700lb higher capacity then the DK35 loader and I use every pound of extra lift daily, moving dirt, rocks, stumps, gravel, snow.
Price out what each implement is costing separate from the total sale price and post back.