Can car seats go on the fold down in back of a gmc sonoma pickup?

No, car seats generally cannot be installed on the fold-down rear seat of a GMC Sonoma pickup truck. The fold-down seat isn't designed for the secure installation required for a car seat. The lack of a proper anchor system (LATCH or seatbelt anchors in the correct position and strength) makes it unsafe. Using a car seat in this manner could lead to serious injury or death in an accident.