One of the reasons for the price difference when ordering a Newmar, is that the Spartan had a five year chassis warranty and Freightliner only had a three year warranty. The price difference used to be about $5K.
However, for $1800 you can extend the Freightliner chassis to five years, as long as you do it in the first few months of ownership. I extended mine, giving me a five year warranty on the chassis, engine and trans.
Don & Mary
2019 Newmar Dutch Star 4018 (Freightliner)
2019 Ford Raptor