What was the last year for the 299 that was not a DEF machine?
You can't go by "years" because changes of model do not necessarily happen at year end or anywhere near it. As far as I can see the following 299 models were not equipped with any form DEF system. All D models have exhaust aftertreatment but the earlier ones were Tier 4 Interim and didn't use DEF. 299C - S/N prefix JSP. Manufactured between 2010-2013. 299D - S/N prefix HCL & NLC (XHP). Manufactured between 2012-2013. 299D - S/N prefic GTC & JST (XHP). Manufactured between 2013-2015. There may have been some later models than the list above. All 299D2 and 299D3 models are rated TIER 4 Final and have a DEF system as part of the aftertreatment group.