Hi tsmith,
I suggest you have your VIN handy and call Heartland Customer Service, 877-262-8032 / 574-262-8030. Ask for parts department, I would think it might cut out a couple of people and give you quicker results.
Jim M
Tim, I just went and checked my unit, I thought I remembered seeing a tag. Mine has a tag on the hinge edge of the door. Gives part number and size and some initials. Yours may have it also and could speed things up.