Leah,
It's easy to check to see what type of axel you have. Just look under the caoch, if it has a solid steel axle running from side to side, it is fixed. Make sure you take it to a shop(like Josam) that can check and align front and rear axles. I had a serious problem with wear on the driver's side steer tire and found it was caused by the tag axle being out of alignment. The tech who worked on my rig found the drive and tag axles both out. He told me that the majority of motorhomes he works on that have alignment problems have drive or tag axles out of alignment. Apparently, the chassis manufacturers buy the axles from suppliers, weld them to their suspension systems and they get deformed by the heat.