I’m not sure if that statement was 100% accurate, but it was certainly based in reality. California will not register diesel powered vehicles with GVR over 10k (maybe 14k, not sure) after 1/1/2020 unless they have a certain model year engine and associated controls. Perhaps that year is 2007? Essentially they will require DPF and Catslysts. This may only apply to commercial vehicles? You might also be able to register as an RV? I’m not sure, my company only had one truck and we scrapped it, so I didn’t pay much attention. I don’t know about the rest of the US, but you can hit the CARB website for more information about the “truck and bus rule”.