Hi Widowson,
Welcome to the Heartland Owners Forum and hopefully to the family. We have a great bunch of people here with lots of information and all willing to share their knowledge if needed.
I would suggest you call Heartland Customer Service, 877-262-8032 / 574-262-8030, and ask for the MPG section and they should be able to tell you where you could look at a MPG 181.
Enjoy the forum.
Jim M