6v Battery Guts

Has anyone ever dissected one of the blue 6v batteries from the old Lightning McQueen cars? The upper section appears to be a separate plastic piece, and I suspect it’s just a cap covering the battery terminals.

We have a bunch of Lightnings with dead batteries. The replacements are absurdly pricey. If possible, I would like to salvage as much of that wire & connector as possible and just put them on a standard 6V 4Ah battery.

(To be clear, I am NOT advocating that anyone try dissecting a battery housing; just curious if anyone already has.)