I need a drivers side power window switch for my 89' turbo. Do I have to get a s5 switch or will the s4 work too? I see some on ebay that say they work for all years, but victoria british has two different part numbers for both series.

 

as far as how they wire, yes both series are the same and will plug in and work fine.

However, internally the S5 switches are garbage and built completely different.