Imbedded antennae

[1968F100]

I own an 03 MM and a 07 GM. Both
Have factory head units, but it seems the 07 has much clearer and long distance reception of radio stations. I have a couple of questions.
1. Do you think this difference lies in the antennae or the head?
2. Will the back glass swap from the 07 to the 03?

Any input of value is appreciated.

[fastblackmerc]

Aftermarket head unit.

[Spectragod]

Connections on the glass are different between 03' and 07'.