Re: Oldfast bait...
There is definitely no back plate relocker in these locks.
I'm speculating, but I suspect the reason for this is that a back plate relocker comes into play when the dial spindle is subject to a punching attack. A punching attach on this lock will at most only break away the cog that is coupled to the spindle, so the wheel pack does not end up exposed, as it would with a direct drive group 2 lock. The opening created by punching the spindle would be quite useless.
The other scenario when a back plate relocker is helpful is when a safe is drilled from behind, the back plate unscrewed & the wheels scoped from the hole in the back of the safe. Given that these locks are used on vaults means that rear drilling of the container is at worst highly unlikely & the chances of successfully removing the back plate via such a hole are very remote. In situations where this is not the case, a relocker that is external to the combination lock can perform the same function as an internal back plate relocker, although it would presumably act upon the main boltwork of the door.
...Mark