I'm afraid I can't be of much help here.
HysterUSA does not list an A232.
I can find all you'd ever want to know on A231 and A233 but nothing on A232.

What I can tell you is that 18,000 - 23,000 hours on a diff in a H100 is not that bad.

At 4,000+ hours/year you are on the heavy side as far as use.

If those hours are mostly under heavy load then you are doing all right.

Maybe you need to teach us how to make our trucks last longer.

Sorry,
Mike