I just replaced both batteries on my '03 Friendship Quattro about 6 weeks ago. They are threaded terminals.
I went to the nearby NAPA store and they were unable to get a match by vehicle model and make. I called the dealer for a part number, but they couldn't find anything, so they called the factory. The part number provided by the factory did not cross reference to anything in the NAPA book.
I removed them and took them to the NAPA store and they were able to match them up. They do an exchange so, I had to take them there anyway.
They are fairly common commercial grade batteries. Very easy to install and their price was quite reasonable compared to the RV dealer or Freightliner. Beside NAPA, they are probably available at Batteries Plus and at some auto parts stores.
http://www.batteriesplus.com/store_loca ... te/wi.aspx