86Regency

I have a 1985 Oldsmobile and need to replace the struts in the back, since it is sitting low from the back now and does not feel smooth as it used to anymore from the back.

The thing is that every time I turn my car on, I hear like an air compressor turn on and then off, the same thing happens after I turn my car off. Is that because my shocks/struts are air operated, because they do have this cable plugged in to them. If you need a picture let me know I'll upload one to make myself more understandable.

Please, let me know what brand and kind I need to get so I can still get the same or even smoother ride in my car, but also strong where I can carry some people in the back.

Thanks in Advance