I have a 2005 370, so I am not sure if it is the exact same, but I just went through the microwave buying process. It was rough. I ended up emailing IP to ask them which, if any, specific model would fit and they told me "a small one".
Our "microwave hole" is 19 wide, 9.75 tall, 12 deep.
I eventually bought a Proctor Silex 0.7 Cu ft Black Digital Microwave Oven from Walmart:
Proctor Silex 0.7 Cu ft Black Digital Microwave Oven - Walmart.com
It fits the hole. It is a boat though, so your mileage may vary. I hope this helps.
