diesel fuel nozzle

Depends on the station. I have been to some where the large nozzle fits and some the large nozzle has a sort of mushroom tip on it that flares out. I assume this tip is a sort of safety lip so it catches the edge of the tank and doesn't fall out as easily if left unattended. This lip was way too big to fit into the filler neck of my truck.
Generally you see truck stops will have a separate diesel island for us. If I see these I automatically assume that these will fit.