SL55 Sat Nav change

[Sump]

When is the official change for the widescreen nav in the SL as it's quite confusing.

I've seen:

SL500 54 with widescreen
SL55 05 with 4:3

How does that work then?

[JohnRS4]

My sl55 is 54 reg and has widescreen. Introduced for 2005 model year cars. The 05 reg with small screen must have been 04 model not registered until 05.