Is purchasing a truck in installments from Al Rajhi Bank impermissible (haram) or permissible (halal)?

It is not possible to rule on the permissibility of the bank financing transaction due to a lack of knowledge regarding its specifics and conditions. However, Al-Rajhi Bank is considered one of the Islamic banks, and it is most probable that the transaction was conducted as a Murabaha in stocks. You can inquire with the bank's Sharia Supervisory Board. There is no harm in benefiting from what is earned through working with the truck, even if the transaction were deemed impermissible; this is because the impermissibility is related to the liability of its owner, not to the specific money earned from it.