My odometer has been messing up for a long time, getting stuck on the trip meter then it will switch to the odometer, usually in extreme temperatures. Most of the time it straightens itself out but this past week, it is just stuck on the trip meter but displays random numbers every 3 minutes or so as I'm driving along. I'm getting ready to sell it and I don't want to fix the problem so how can I know the mileage to sell it?

There may be technical service bulletins that apply.
Read here:
https://www.askmehelpdesk.com/cars-trucks/when-asking-about-your-vehicle-303903.html

Then we can talk...