Hard to say, it's one of those "is some rich guy looking to hype it up and put it in Mecum?"
Because really it is a standard cab, shortbox 2wd 1990's pick up truck with some stickers on it.
Now, in WI in the salt, a truck in clean condition is extinct. So that means something yet.
Personally, I think it is worth $8k in nice condition. You could add a bonus $5k for the miles on it. If you brought it up north in June into the salt belt you could add another $2k.
But then you need to subtract whatever transmission thing you have going on. Get a quote on full rebuild if you aren't sure. Could be as simple as it didn;t like getting less than 1000 miles a year on it and the converter is slugged up and needs a good flush etc. Or it could be a factory dud, a couple of those made it out to the public to keep the "dodge transmissions are all sh4t" theme alive and well. It would be really bad luck, but it could be.
It is a pace truck, not an SRT10, not a Ford Lightning, Chevy 454 SS, Typhoon, etc.
You either need to keep it how it is for another 20 years or plan on it being a fun driver. Fun driver doesn't mean a lot $$ wise.