My sister in law gifted us a truck. I ended up selling the truck because it was just too big for me to drive. Do I claim the sell on taxes? If so what form do I use?

You would only claim this as income on your tax return if you sold the truck for more than what it was worth when she gave it to you.  This rarely happens with a vehicle, as they tend to depreciate over time, even just a small amount of time.  

If you feel like this was the case you would report the capital gain - the difference between the value of the truck when you received the gift and the value when you sold it. 

This would be reported in TurboTax under the section for Investments. 

To report a capital gain search the term capital gain income in the search tool in the upper right of the program and then click on the Jump to link that appears in the search results.