The Slave Cylinder is easy to change, and does not require the change of the transmission.
Peter at SBC sells an upgraded 2-part Clutch Master/Slave combo that is heavier duty.
I would start there, they (the slave) will fail and you will not be able to get it out of gear.
One other thing you can check, remove the slave cylinder and start the truck.
NOTE: You will need to jumper the clutch startup switch, do not step on the clutch when the slave cylinder is out of the truck, you will shoot brake fluid everywhere and probably loose the ram out of the slave cylinder!
With the engine running, you can take a screw driver and gently insert it into the the location of where the slave cylinder was. Place it against the back of the clutch release fork. DO NOT stick your fingers in there!
If you feel excessive jerking, then you might have damage to the clutch/pressure plate/release fork/input shaft.
If you are going to change the clutch, I would just upgrade to an FE. It drives almost the same as stock. I personally do not think it is worth only going with the OFE (you will understand if you pull the transmission).
-Rich