Sorry, before I misread it and was thinking you were looking for a PCB. Easiest way to know the family is by the letters in the code after the dash. I've kept a list of that going too, but I know it needs some updating. Here's that list: https://www.data-medics.com/forum/ident ... -t636.html
For 500Gb Zephyr's you're looking for
WD5000BPVT or WD5000BMVV or WD5000BMVW with a code after the dash containing either AMCS, HXZT, or SXZS
You can also pull heads from a 750Gb model in that same series, it might just have an extra head you don't need in some cases.
In the DCM you just need to match the 2 or J and the letter directly before it. I often try to match both of the two letters just before it, but it's not entirely necessary (e.g. NT2 or HTJ, etc.).
Beyond that, just try to get same country (pretty important) and as close a date as possible (very important).