Note the "2004" on the stickers.Yes indeed, super easy to replace. Can do it in 5 minutes each. And yes, they are a bargain!!
I'm a bit leery of these "New Old Stock" parts, especially after seeing a forum member's clamshell with brand "new" struts blow shut in a light breeze. Sitting on the shelf seeping nitrogen for 12 years.
I'm going to spec some struts from McMaster Carr. $17 each. 15.24" is the correct length I think. Just have to figure out the right extension force. Weight of clamshell on a bathroom scale divided by two, and add 10 lbs each for wind resistance.