Hi
Before you get to cozy with the single rear wheel F350 you may want to look at this post.
http://www.montanaowners.com/forums/...95#post1062495
The single Rear wheel F350 will have the same axle as your F250.
The F350 DRW has a heaver axle in the rear and will have a higher GVW and GCW rating.
Phil P