Hey John...there are so many different model numbers, I can't tell the difference by the number alone. Do you have a pic of it, or can you look at it? The easiest way to tell is the location of the control panel. On the 1st gen models, it's toward the rear edge of the top of the cabinet. On the new, 2nd gen models, the control panel in still on the top of the cabinet, but it's right in the front.
Another giveaway is the location of the exhaust vent. 1st gen model, the vent is near the right rear in the top of the cabinet...the 2nd gen models, the vent is on the left side panel of the cabinet.
Does that help?
Red