Generally, no. Pickup trucks, especially smaller ones, don't have the same kind of integrated seating structure as cars. The rear seats are often bench-style and lack the necessary anchor points and structural integrity to safely install a rear-facing car seat. Furthermore, the relatively small size of most pickup truck back seats makes it difficult to install a rear-facing car seat without significantly impeding access or comfort.
While some modifications *might* be theoretically possible, they would be highly unsafe and not recommended. Always follow the car seat manufacturer's instructions and the vehicle's owner's manual for proper installation. If you need to transport a child in a rear-facing car seat, a car or SUV is a much safer and more appropriate vehicle.
