Michael I have the same exact truck. If it's original it will have a torque-tube front shaft. Notice the ball & socket type joint on the tail end of the transmission. That covers the front U-joint/trunnion-bearing. Oil from the trans lubes the U-joint. There is a thin metal tube that covers the drive shaft back to the carrier bearing. There is a seal back there that leaks. I think the Truck Shop Manual has an illustration of this. I don't know if anyone repops that seal. Good luck.
