When you are entering your business expenses, navigate to the vehicle expenses.
Choose to use actual expenses for your truck.
When TurboTax asks about the cost of gasoline, oil, etc. use what you paid in 2018.
Answer the next series of questions, and tell TurboTax the date you bought the truck. Then TurboTax will ask what you paid for the truck ($20,899). Enter that.
If you are asked what MACRS convention you would have used in 2001 (quarter-year or half-year), fortunately after all this time, it won't make any difference. Just answer "half-year".
If you took any Section 179 depreciation back in 2001 (I am not even sure it was available then), enter it - if you have no idea, enter 0.
TurboTax will eventually ask you how much prior depreciation has been taken. Since the truck has been fully depreciated, the original price of $20,899 should already be in the field. Leave it.
Eventually, TurboTax will ask you the sales price of what you sold the truck for in 2018. Enter that, plus any costs of the sale.
Now TurboTax has all the information it needs to calculate the gain.
Simply put, the gain is the 2018 sales price less the cost of selling it in 2018 less the original purchase price less the amount of depreciation. Since the amount of depreciation after so many years will be the same as the original purchase price, the gain will be the 2018 sales price less any costs of the sale.
