Suzuki three-pot chassis number engine codes

[Andrew 21 Edney]

A bit of a nerd question here, but there seem to be at least two engine codes used for Suzuki three-pot chassis numbers:

• Z2 - which is listed in the FAQ for what chassis numbers mean
• Z3 - which is not listed, but seems to be used for a mix of 160, Sprint and SuperSprint chassis numbers

I'm guessing that the code might be date related (so cars before 2018 had Z2 and those after had Z3), but that is an assumption on my part based on a very limited set of data.

Is anyone with a 160, Sprint, SuperSprint or 170 able to provide some clues as to whether there was ever a Z1 code, if there is something else used in addition to Z2 and Z3?

Thanks,
Andrew