What were they thinking? Maybe, "It works - reliably." From ChevyTrucks.org
And, from Jim Carter's wbsite:
Closed Driveshafts Forever
Occasionally we hear owners condemning the closed drive shaft system used in the 1/2 ton trucks prior to 1955. After questioning the negative comment, we almost always discover the real criticism is the low gearing of the ring and pinion in the differential. Yes, this lower gear ratio was created more for slower roads of year gone by, but it is by far not a poorly designed system. In fact, it is questioned if there has ever been drive shaft and u-joint combinations that exceed the durability of this GM quality engineered closed unit.
Over 50% of the surviving older 1/2 ton pickups continue to use their original closed systems. Of these, the majority have had little or no servicing other than keeping lubrications in the transmission and differential.
Consider this when you realize the last GM closed drive shaft system was produced in 1954. Many others have been in irregular service prior to the 1920’s. Also remember that many 1/2 ton pickups were often given abuse far in excess of the manufacturer’s recommendations.
What modern open drive shaft system has been able to compare with this unsurpassed record? None!! Sure, the newer open u-joints are easier to change. They better be. They require attention or replacement so much more frequently!
Another Example of GM Quality!!!
We recently received the following comment from John Berkeley Ball. He also confirms the quality of the General Motor's 1/2 ton closed drive shaft and differential.
Dear Jim Carter
Thanks for your excellent articles. One very pertinent point I feel that you should mention about closed drive shafts is their absolute impervability to rear spring wind up. Used on the farm over soft ground with heavy loads, you could not afford to send your rear end into drive breaking pulsations every time you lost traction, whether the shocks were worn out or not (some were single action any way). What a huge advantage over the Hotchkiss rear end! this is an often unknown design attribute that Chevy engineers were unfoundedly maligned for - at least by today's city slickers...
You may relate comments to this web site or Mr. Ball direct at firstname.lastname@example.org.
(sorry about cut/paste from JC site, he does not make linking to his site very useful)