Engine exchange

[JagWhite]

Hi erveryone,
I just bought a 72 E-Type 2&2, a Belgian car, and I found this small plate in the service book:

Indeed, the number on my engine (7S1595) does not correspond to the original engine number (7S5125).
So I guess the engine was changed at some point, maybe by Jaguar. Does anyone of you know what the numbers on the plate mean? If it was changed by Jaguar, is it marked on the Heritage Certificate?
Thanks for your help and many greetings from Luxembourg.
Gilles

[JagWhite]

Hi,
I've just noticed that the suffixes on my engine number are SBZ (7S1595 SBZ), and the Z seems to be stamped on later, it looks a bit different than the S and B.
Anyone knows the meening of the Z?
Thanks,
Gilles