I bought 2 Group 27 batteries from the Mall,no problems here.

I have a red cap turbo start battery that just died. Also had it since 2011, too bad it finally gave up. Anyway, what are you doing to gut it and replace the insides? What have you bought to go inside, or are you not that far yet?

I did mine, unlike others I have seen I cut the top off to be used as a lid. This also left the whole case intact.
I treadled the post and screwed the post in but may just bolt a cable to them and then onto the new battery inside.
I also epoxied some plastic angle {like angle iron} to hold the top in place but the factory hole down would work. I kinda go past what is needed at times.
I polished the rubber case as seen in the picture with Yellow Caps. And have 2 sets of caps in case I want the 24 to look like a 27 I kinda go past what is needed at times.

I am maintaining my Odyssey PC925 on a Battery Tender Jr even though it’s not recommended. IMO the charging issue boils down (ha! Pun intended) to whether or not the Charger reaches float stage and drops voltage down to around 13.3, which last I checked mine does.

I wish someone sold just the cases, so people can modify their own. I think folks would buy more of them if they had an option.

I gutted mine as well. I don't remember how long it lasted, but not more than 3 or 4 years at most.

I put a Odyssey PC925 in it. That was 3 years ago, and it too is starting to crank slow. But better a $157 replacement.

Should have taken more pictures, but here we are.

Good job.
I seen guys who cut bottom put but cutting the top off to.me is the way to go.