Totally. The OEM was junk - see the threads about the cracks in those original roofs thanks to poor factory installations - and leaking despite about 30 pounds of caulking. Get with Inland RV. We just bought a new roof window from them via the web site for our 08 International.
Take the measurements, talk to Inland. Check the thread here for how to remove the old skylight.
I used Sikaflex caulking and not the 3M Marine 5200 which I hear is NOT right for plastic skylights. Remove the old skylight by leveraging a strong putty knife under the edge and between old caulk and metal frame. Scrape and wire brush the old caulk down to bare metal.
Line up your new window on the clean metal frame around the window opening. Don't use the original holes in the metal frame. So you have to line up the new window and mark new locations. Be careful not to drill too far towards the edge of the aluminum frame.
Carefully first drill the skylight holes as marked. Then set the skylight onto the metal window frame, its holes lined up where you want, and drill through the aluminum using the plastic holes as a guide. The plastic holes are larger than the aluminum ones. Inland gives you the correct sizes. They were great to talk to on the phone too once I had all my parts together and was nervous about where to begin.
I used a healthy bead of Sikaflex on the aluminum, got sheet metal screws with built in washers, added rubber washers. Set the new window down on the frame, press it into the Sikaflex, align the holes. Then I put a good dose of caulk in each hole and screwed down the screws by hand, not with a power tool so as to not over-torque the screws and crack the window. Check out your processes, your measurements, your replacement size, the caulk, screws and so forth. It took me the afternoon to do it carefully. Oh, and stretch a sheet of plywood on the roof between rafters to allow you to step carefully on the roof.
Good luck. Inland was a big help over the phone. The new window looks marvelous. No leaks, either.
Jim and Marsha
"Stream of Consciousness"