I got the build sheet on my old rig I purchased used.
I contacted Coachman for my unit and supplied my VIN #. The customer service rep was able to pull the build sheet, explain the options I had and sent me a copy.
Here is a good starting place for your Forester.
Forest River RV Contact Us - Forest River, Inc.
Select Forester from the drop down on the "MOTORHOMES" tab.
I also requested and received a build sheet for my Salem Villa Estate through the Salem Villa division via customer service.