1839 inline upgrade to 1840

So looking to possiabily upgrade to an 1840, however I'm having a hard time spending a ton of money to purchase this 1840. I'm trying to wrap my head around the small differences and why the changes can't be adapted to my current 1839? To start I see augers are reversed flighted, which I see no reason 1840 augers won't work. Next the stuffer, and the part I'm most interested in, we all know the stuffer is the most challenging on these balers, but why couldn't the 1840 stuffer work? Big 1840 twine boxes are easy enough to add. Help me out please, also if someone could tell me about advancing a tooth on stuffer that would Grreat

1839 inline upgrade to 1840