Does this watch come in an x large?

No....it says extra long which is why I purchased it for my Father. His wrist measures 9" around. It was too tight for him, so I'm not sure if it's a misprint but it is not extra long or does it come in any size but a regular mens watch. Hope this is helpful info.'

Good watch but horrible stretch band which I replaced with a leather band. It comes with indiglo backlight.

Why are the model numbers different ? Timex and the sellers ?

That is to stop people from cross pricing these watches. This watch can be found for as little as $ 38.00 to $ 45.00. Sellers can make you believe your getting a higher model watch when your not.

what is the diameter of the watch band when on the watch?

With the watch not on my wrist I used a tape measure and went from the dead center of the glass face around the watch once and it was 8 inches total. This is an expandable (stretch) band. I have a big wrist and its a little tight but it does stretch on okay.