For anyone who has never seen nor heard of a torque-tube enclosed drive-shaft, Dave's question is one of the first for a person looking at at pre-55 1/2 ton (and other) Chevrolet truck.

http://en.wikipedia.org/wiki/Torque_tube

"The torque tube driveline is also used in Sprintcars and Midget cars. The C5 and C6 Chevrolet Corvette, Lexus LF-A, Porsche 924, Porsche 928, Porsche 944, Aston Martin DBR9, Aston Martin DBS, Aston Martin DB7, and the Mercedes AMG SLS also use variations on this design, mostly with rear-mounted transaxles."

Used on a modern Mercedes

Used on mid-50s Ramblers

I guess our 1/2 ton torque tubes are live axles with no pan hard link?