For all model years, including 1989 911 Turbo's, there were several options for the radio/cassette player. In fact, 1989 offered the first Porsche branded CD player, which is seldom seen. Here are the radio options according to:
https://www.stuttcars.com/technical/option-codes/911-84-89/
326 Cassette-radio Blaupunkt Berlin IQR 88 on MY1989
327 Cassette-radio Blaupunkt Bremen SQR 46 from MY1986
329 Cassette-radio Blaupunkt Toronto SQR 48
330 Cassette-radio Blaupunkt Toronto SQR 46 from MY1987
690 CD-radio Porsche/Alpine CD-10
691 CD-radio Porsche/Alpine CD-2
The Bremen is common, as is the Toronto. You would have to have the Cardex on your particular car to know for sure, but either of those two are legit for your Euro 930.