e46 radio is easy to remove (but you do need to remove the passenger side trim piece). It would take you 10 mins to check and see if the antenna is plugged in.
You might want to pick up one of these:
https://www.amazon.com/Original-Carl...ly+bmw+adapter
It works as a code reader and basic programmer for BMWs. You'll be able to code your door locks and lots of other things on both your e46 and e90.