I’ve looked at the GC 2’s at Sam's. Looks to me it requires a modification to the battery tray to fit the 2552. Don’t know how difficult that is.
Our 2007 PC battery compartment was the first year of two batteries in a slide-out tray on the passenger side mounted below floor level. I believe it is the same as all subsequent PCs with 12V batteries in a slide-out tray.
Some time over the years, Phoenix changed from two 12V batteries wired-parallel, to two 6V batteries wired-series, but I don't know if 6V batteries are still installed in new PCs today. Phoenix might have switched back to two 12Vs.... though I could not imagine the logic behind doing so.
Anyway, because 6V batteries are taller than 12Vs, I had to replace the slide-out battery tray with a steel stock plate to gain the extra height required. The plate I had around the house has a few bends in just the right places for the application. I cradled the batteries on the plate as shown by
CLICKING HERE.
Because I deleted the slide-out tray, I went with sealed AGM batteries as they require zero maintenance. I arranged the batteries with + and - terminals placed properly for ease of external charging and jumping which also works well with a kill-all disconnect switch that I added more recently.
For reference,
CLICK HERE to see pictures of my original 12V batteries in the original slide-out tray. This photo album was made to show how I added a protective splash shield for the batteries from the rear tires. I don't know how Phoenix is protecting the batteries from the rear tires today, if they have since done so.