it's probably more similar to the Rubicon than the 420 though lolHe's yanking your chain. Forward him this link if you have to.
It's a 2004 to 2007 Honda Rancher AT. Also known as a Rancher 400. Also known as a TRX400FA or TRX400FGA if it has GPS. It's a 398cc air cooled, carb'd ATV.
The 420's all are 420cc, EFI, and liquid cooled. Have him show you a picture of the engine and carb and then say "gotcha".
It's definitely NOT a Rubicon for many reasons.