For anyone challenged with installing the Atwood Springlift struts used to hold the external storage bays open, We had to replace one on our '03 this past summer.
We found a 24" QuickGrip clamp worked great to compress the strut to the proper length allowing it to pop right on the pins. The most common clamp models are rated for 300 lbs, which was plenty to compress the 100-120 lb. strut. A pipe clamp would work as well (but Steve appreciated the new QuickGrip since he'll put it to use in his woodworking adventures in the off season).
Just be careful as you are dealing with a lot of pressure with something that could cause serious injury once the strut is compressed. Make sure that strut is straight in the clamp. Wear your safety glasses and keep your head/face/important body parts out of the way.
The numbers on the old strut should tell you what psi they are, I think ours was 120. The factory can also tell you.
Replacement was very easy this way. I held the bay door steady, he applied the clamp with the ends rotated so they lined up with the bay hardware, and there ya go. Michelle '03 U320
Another way to compress them is with a ratcheting nylon band clamp. Also a good way to compress gas-filled shock absorbers for installation. Dave Katsuki 1999 U270 36'