If you choose gauge mode on your dash it adds the def gauge
For the 2.5 gallon.....at convenience stores its $14-17 its around $12.50 at Walmart/Costco but I have been filling it up at truck stops where they sell it at the pump by the gallon last time was around $2.97 I topped it off . seems like it was cheaper a couple years ago. I remember it being under $9.00 for 2.5 gallon at the convenience stores. I will say the 6.7 Ford uses much more than my 2015 Chevy d max.How much are you paying for DEF?