I have that exact same thing. Paid $225 for mine, used, but in new condition.
That diffuser box is a great thing. I still don't use the bottom rack much though as it runs about 100 degrees hotter that close to the FB. Congrats on the new addition to the family!
18.5", 22.5" OTS
Large BGE (chambersuac's)
The Fiery Furnace (chambersuac's)
Big JT's Smokin' BBQ Competition Team