Should only have to match the specs for a replacement drive. 8TB, 5400 RPM, 6 Gb/s, 256MB cache according to a quick search of wd80efax-68knbn0
https://www.amazon.com/Western-Digit.../dp/B07D3MWMNZ
Be warned, OEM drives usually don't come with any warranty:
https://www.amazon.com/OEM-Drive-dri.../dp/B00V5I65NW