Here is a post with all the DSP amp part numbers I know about. I would recommend that you use any of these that is part number -119 (yours) or newer. You can use an amp from an E53 X5, E39, or E38. Unless the donor car is nearly identical to yours, you will likely need to get the amp coded once installed.

Xoutpost.com - View Single Post - Can my Amp be repaired or will I have to buy new

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2000 E38 750iL Highline Edition, Upgraded with the lastest 2006 X5 Electronics
MKIV Navigation, 16:9 Display, Bluetooth, TV/Video with Backup Camera, Sirius, and Aux Input