981 and 718 rear tuning forks interchangeable?

[andygo]

I'm looking at replacing the rear tuning forks on my 2016 981 CGTS.

As the 718 version is about half the price of the 981 version, but look the same and attach to the same part numbered coffin arm, I wonder if they are interchangeable? If not, why not?

718 part number is 892 501 401
981 part number is 981 33104 303

Thanks