Monaco (manufacturer of the Holiday Rambler Navigator) made a few changes from 2004 to 2005.
The first year for the Intellitec Multiplex system was 2005. This system uses programmed multiplex modules and lighted wall switches rather than the previous individual rocker switches.
2005 is the last year for the Trace Xantrex inverter. In 2006 they switched to the Magnum inverter.
The television size and type was updated in 2005, but both would be outdated today.
The big change is the interior ceiling height was changed from 79" to 82" in 2005.
The other big change is the 2005 model can have the optional 515hp Series 60 Detroit or 525hp Cummins ISX with the 500hp Cummins ISM as standard. The 2004 came with only the 500hp Cummins ISM (which is a great engine). However, I've heard of a few late 2004 models getting the optional engines that came in 2005.
Both model years come with the Onan 10,000 diesel generator. Only the Signature and Marquis have the 12,500 Onan generator.
You can download and review the Monaco Executive brochures from 2004 and 2005 for a good comparison. Except for the front and rear cap, they are almost identical.
Hope this helps.
97 Monaco Windsor- Sold
07 Monaco Executive McKinley- Sold
04 Monaco Signature Chateau IV