2008 DS90X rear shock rebuild or replace?

Hi,
I can’t find any information on rebuilding this shock and I don’t have it with me. Can these shocks be rebuilt? I asked the dealer if there is a kit and they can’t find one. I don’t want to spend $400 on a shock for this.
I looked at kayaba’s site but am not sure what kit will fit. The shock is a HPG which from what I understand is a KYB shock (Kayaba). I’m thinking their measurements are of the shaft but what about the body of the shock?

Some help would be greatly appreciated!