I have found out that swapping PCB of drives with identical part number, MLC and firmware doesn't result in good working drives. My question is:
Is there any adaptive data stored in the NVRAM of these drives?

It depends on which model hitachi drive it is.

For example, the ATMR series needs to have the NVRAM moved to the new PCB as it stores adaptives.

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Data Recovery Ireland

In most of the hitachi/IBM drives there is a nvram which u have to swap while changing pcb to make it work .

It's not true for the old IBM drives from DTLA, AVER and AVVA families if the Partnumber and MLC of both drives are identical.

I'm interested about the newer families - PLAT, VLAT, DLAT, etc.

For IBM i swap nvram to make pcb work never paid any attention to Partnumber and MLC code for pcb swap . PLAT has nvram to store adaptives so u have to change it to make pcb work .