[AT] OT truck tires/driveshaft?

[jtchall at nc.rr.com]

Checked the driveshaft, everything seems in line.

Pulled off the one inside dual that has a known flat spot and replaced with 
a spare and took it for a short spin with just the one tire on that side.

Wound it up to about 40 in 3rd and held it, got a different 
vibration--different frequency, more of a smooth vibration instead of the 
violent shaking the cab has been doing. In 4th gear still getting the same 
vibration. Could it be an axle or rear end problem?

For the heck of it I started checking for used tires---I need them 
regardless of the vibration. Every time I've looked in the past there were 
none to be had near here, now I've found 2 sets of really nice tires. One of 
the most common used tires to find is military. Are they any good for 
running loaded heavy on the highway? I would imagine they are more suited 
for off-road?

John Hall