The GPS receiver module (also called the "Trimble Module") is a factor of which navigation computer you choose. The MKIII and MKIV both have internal GPS receiver modules. The MKI and MKII have external GPS receiver modules. You got a MKIV, so that has the internal GPS receiver module.

You will need to get the GPS antenna and GPS antenna cable. I am pretty sure that those two parts are not pre-wired in an X5 without navigation, no matter which model year you have.

Here is a post that gives a breakdown of BM53 radio modules by part number and features. There is no easy way to confirm the features of a BM53 radio module

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SOLD
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