Don't have a good current answer for you. My old 7.3 diesel didn't matter and it loved Pemex diesel. My newer 6.7 has enough range from filling up in Ajo to make it to PP and back again, so I haven't bought any diesel in PP.
Assumption on my part -- a lot of the gas/diesel sold in Sonoita/PP was refined in the US, so I'd like to think it meets ULSD content limits.