there is no explicite information about the S2 model.
I have picked the main criteria in my description before.
When selecting spare parts for your Twin, you can use the wide range of the Z750LTD Twin model Y1 (1982). Motor is the same type from B3, B4, LTD Y1 and CSR. The LTD K1 (BD) motor is different.
S2 models use front brake and maybe front fork parts, which is more equal to the Z750LTD Twin BD (belt drive) K1 version.
You may visit the german Z750Twin website in english version by clicking the green, round logo and link left hand side.
Go to “Twin Modelle” at the home page to see some different twins models. From there select “Typenliste” to see a description of the different models.
It may be that your Twin was changed either to the dual disk brake from a S1 model to the S2 standard or it is a S2 model with the “older” Y1 motor, not sure.
What is the date of initial registration? 1982 or 1983? Or even later, which doesn’t help!
Yes, there are many different Twin models out there. B1 to B4 is easy to differentiate, but the LTD models where mixed during the few years of manufacturing!!!
There are also differences in the various country versions of the LTDs.
Doesn’t matter if you have fun with the Twin ;-)))