2015 800 Outlander diff question! help!

Hey guys, new to the forum and new to can am, drove a 1991 300 honda prior to upgrading to the 800 outlander and love the machine. However, the maintenance is much more than what I’m used to. I changed the front and rear diff fluids today, and according to the manual you are supposed to fill the front diff to the fill plug and the rear diff to 1 inch below the fill plug. The front diff was easy however rear diff was tougher to tell when I hit the proper full amount. When I started the bike it seems fine however in reverse it seems to have alot less pull, as if something is slipping! Help! :th_smiliefrustrated