Here's what SOS said to me.
"Thank you for using the Department of State's web site.
The body style will depend on what type of box or flat bed is used to complete the vehicle. If it has a pickup box, it will be titled as a pickup and same for the flat bed = stake truck.
Either way the completed vehicle will need to be weighed - you will need a certified weight slip - and you will have to provide bills of sale or an invoice for the body/box/bed that you placed on the the truck. If it was completed before you bought it, you will have to complete a statement of such and identify the type of body - flatbed/stake or pickup.
If you have other questions, feel free to contact us at 888 SOSMICH (888-767-6424).
Department of State Information Center"