I've got a MK3 system with wide screen display in my 2002 E46 M3, I'm considering upgrading to a MK4 system.

But there are a hell of a lot of differring mk4 part numbers out there...

Is there any real difference between them? (if I buy an early unit am I ok?)
I understand I can recode if I get a monochrome display?

(sorry if you see this question a lot, but I could not find the info using the search, maybe bad search terms)

Thanks