2001 X5 With Rear (only) Airbags shocks

[ruskie34e36]

Hey guys,
Before anyone says it, i've searched for the answer prior to asking
I have a 01 X5 manual, sport suspension (??), with mcpherson struts up front, and air springs/bags with what seem like regular shocks in the rear. Now,
ocasionally i load the car up, and as with my other bmw's i like to go thru them and replace the normal wear and tear things, and freshen up the ride.

The front - self explanatory, nothing unusual there.
The rear - if I wanted to replace the shocks, what part number are they? Most places carry shocks for either "self-leveling" or "non". Is mine considered self leveling? I've noticed it maintains the height in the rear with load/trailer hooked up, so that would mean yes?
And is there a special procedure to do that? Special draining of the system/refilling with a bmw DIS tool?

Thanks so much in advance