Landing gear is designed to stabilize a portion of your trailer's weight, not to support the full GVWR of your trailer. From what I found online, your 2004 Dutchman Sport 30 has a GVWR of 9,764 lbs, so a set of 8,000 lb landing gear (combined) would be more than enough to support the front of your 5th wheel trailer.
The Bulldog Tandem Landing Gear Set # BD500162, you were looking at, would work as a replacement. There are just bolts already installed where you'll mount your existing motor... view full answer...
For your 2004 Dutchman Sport 5th Wheel I recommend the Bulldog # BD500162 and you'll also need the hand crank # BD500203 to operate it. The bracket spacing will likely be different so you'll have to cut off and weld on the new brackets to match up with the weld-stops on the jacks and then will bolt the jacks to the mounting brackets. view full answer...