hi to all
if you want to upgrade from analog to digital you can do it your self have a look at this site of how to do it
http://pibus.info/tv/ then for the dvb-t tuner or the dvb-t2 tuner you can buy from aliexpress have a look at these options
DVB-T Digital TV For BMW X3 E83
DVB-T TV For BMW E38 E39 E46 X5 E53 X3 E83,Z4 E85
DVB-T2 H.265 Digital TV For BMW E38 E39 E46 X5 E53 X3 E83 Z4 E85 ,Range Rover L322,Rover 75,MG ZT / MG ZT-T
as for the head unit you do not have to change to a widescreen unit if you fit the upgrade tuners to your existing video module it stays at 4.3
have a look at the pibus website it shows how to upgrade your existing video module hope this helps
david