Hi,
The preliminary donor selection can be made on the basis of a small label at the bottom
It should be the same central part of the P/N designation

Mikippp

That's interesting. I notice that the ST1000LM024 model has 3 versions of this code -- G94A, G941 and G141. I believe that the the third digit is the number of preamp channels (1 channel per head). In this case there are 4 channels.

The 640GB (3 heads) and 750GB (3 heads) models also have a "4" in this position.

The 250GB (1 head) and 500GB (2 heads) models have a "2" in this position.

The ST2000LM003 (6 heads) and ST1500LM006 (5 heads) have a "6" in this position.

Perhaps the OP could compile a list of these codes together with the preamp IDs in terminal. I suspect that one of the characters in the code (the 2nd character?) could reflect the manufacturer of the preamp while another (the 4th character?) might identify the actual device.