I'm looking at A WD AC22100 and AC22500 drive.
It does look like the controllers on these drives use connectors instead of direct solder fillets to connect the card to the platters.
So, you do not need soldering skills to swap these.
It still remains, that you need to find the exact same drive for the 'best' results swapping controller cards.
If all the part numbers on the card match between 2 drives, you should be okay.
The AC22100 has a card that covers the entire bottom of the drive.
2 part numbers: WDC 60-600621-004 REV A
and 61-600621-014 A (on white label)
The AC22500 card is 'L' shaped and covers 3/4 of the bottom of the drive.
Numbers: 60-600715-001 REV A
61-600715-008 C (on white label)
My concern is that there is 'firmware' installed to customize the controller card to the platters.
I just looked myself at WD's site and did not find a 22400 either.
This makes me believe that what you have is an OEM drive.
Another possability is that they had a run of drives with a higher or lower yield of bytes on the platter, and gave them the unique number to reflect the number of bytes available.
Chas