Its hard to say. It is a sellers market and it is spring.
I doubt the axle will bring much extra value to the average buyer. If you lifted the htt, that might bring some extra value. To put a hitch on today might be $300 to $500.
When I sell something, and want top dollar. I make sure to have it spotless inside and out.
If in your area they are going for $9-11K, put $11-12k, and negotiate down. Make sure to remove your stuff, before taking photos unless your stuff is super clean and neat. If it is cluttered, people will think it is small. Empty cabinets and their imagination won't realize how small a 17z really is.
2012 Jayco X23B
2020 Ram Laramie 3500 SRW Air ride 50Gal fuel tank.
2007 Dodge Dakota Quad Cab (retired from towing)
Equal-I-zer 4-Point Sway Control