Explanation. The WD family code is found in the part of the model after the dash, usually in the 3rd, 4th, and 5th characters. So for example in a model such as WD5000AAKS-40V6A
0 the family code is V6A, and as you can see below belongs to Tahoe family.
This can be helpful for finding other models that belong to the same family and will be compatible for heads and PCB replacement.
Please feel free to post below any ones that I may have missed or if you see any mistakes. Thanks!
For older families, please visit this thread on DeepSpar Forum: http://www.deepspar.com/forum/showthread.php?t=1295
(Thanks to Yarek)