Thank you for your reply Jared.
Let's talk only about WD400BB or WD800BB series for example. When you say "the head map used on each WD drive is stored in the ROM", do you mean inside the 8-pin EEPROM or inside the bootstrap memory of Marvell 88i65xx chip controller?
I suppose that information is proprietary and only for manufacturers of data recovery equipment. The 8-pin EEPROM in these drives is 128KBytes, and I believe only a portion of them is realy used to store adaptive parameters and so on. The question however, is to know where the specific locations are used. For example, I can see in posts that you talk about, let's say, "module 47". Of course, that 47 is not physical location 0x0047 in the memory map of the EEPROM. I suppose is only a logical identification of some real memory address in the 128KByte span memory map.
Is there some information public available to correspond logical modules to real memory physical locations of the EEPROM, like for example, head mapping and so on?