Your original nav screen would have been the widescreen version in 2002 and is best to find one directly for an e53 since the screen is set a different angle than the e38/e39 format. With regard to the drive in the rear, it was a MKIII CD based and would most definitely look for a MKIV DVD based version as it is so much better and directly compatible, this can be from e46, e39, e53, e83 or e85/6 (2003+) but make sure it has "DVD" printed on the face of the drive. Hopefully no wiring was cut otherwise you will need to get the plugs from a wrecking yard.