'54 and older had the closed driveline. The actual driveshaft and u-joints were inside of a tube that ran from the transmission to the rearend. Starting in '55 the open driveline was used. It's what is used today with the driveshaft and u-joints exposed. Advantages are open to personal opinion, so here's mine. I hated closed driveline. Keeping a truck truly original is the only advantage in itthat I can see. With the open system you have the advantage of being easy to work with, but you lose originality. I guess it all boils down to what you (the only that really matters anyway) want to do with it.
