Traveling through Montana every summer many of the smaller towns have 3 diesel pumps.
#2 taxed - that's the one you want/must use
#2 untaxed died fuel- for farmers and off road use only.
#1 not to be used in virtually all pickups with diesels. Not really sure who uses it.
In Oregon you will often also find 3 choices
#2 taxed state and federal- again what you use
#2 "with PUC permit" Truckers can use this and pay weight mile tax rather than state fuel tax. difference between this is the state $.24/gallon fuel tax is not collected,but you need the proper permit to fill from these tanks.
#2 off road died fuel. Again, not what you use.