diesel fuel nozzle

My 2008 Chevy has the larger opening and I have used the truck pumps many times.

Truck stop diesel pumps are made to fill very large tanks (18 wheeler trucks) and the pump nozzle is larger than the normal regular vehicle fuel pumps. The reason it is larger than normal is to be able to fill those large 18 wheel tanks much quicker.
I believe Dodge Ram trucks were the first to adapt the smaller trucks fuel tank fill opening to be able to use the truck stop pump nozzle. Don't know if ford or chevy have adapted over the years.

Just beware. The tank will fill up rather quickly.

I have an auxiliary tank and it is wonderful to have those high volume nozzles.

Ummh...I stopped at a truck stop to fill up my Ram CTD years ago and got the nozzle stuck in mine. The nozzle was bigger than the nozzle at a normal diesel pump. It took a few minutes to finally work it loose. Things may have changed since then???

Yes the nozzles will fit. The fuel fill caps are designed differently than gas. Diesel is not as volatile as gasoline therfore less likely to cause a fire due to an errant static spark. This is part of the reason why gasoline nozzles fit so snuggle inside the fill cap.