Your loan loan documents describe what rights the lender and its agent, the repo company have, when you default on your loan, and without reviewing your loan documents, all anyone on Avvo can do is guess. One of those rights is presumably to repo the truck whenever they want to. Another may be to report the truck stolen, if by your default you've forfeited any ownership and possessory rights to it. Hire a lawyer to review your loan documents for specific advice.
Disclaimer: Please note that this answer does not constitute legal advice, and should not be relied on, since each state has different laws, each situation is fact specific, and it is impossible to evaluate a legal problem without a comprehensive consultation and review of all the facts and documents at issue. This answer does not create an attorney-client relationship.