Check Realoem for the correct part number for mounting in the trunk. Then talk to your dealer for a price and part number verification. There may be two different types of mounting hardware, depending on the BMW cd changer (BMW Alpine or Pioneer). Perhaps at that point see if you can find used or best price.
As other said, there are three or four pre drilled mounting holes under the left side or deck lid in the trunk for the mounting brackets. The wiring harness should be nearbly under the trunk panels
Others may know, but I believe you must have a 95 specific cd changer. others will not work. Good luck
Thanks,
1995 525i Auto, M50TU 2.5L, EAT chip, 1/95 build, USA, 205/65/15 tires, ASC+T, HID, lumbar, EC Mirror, BMW Alpine 5 radio with BMW-Pioneer CD Changer, abt 236k miles, Oxford Green/Parchment