The reason for the "lumber wagon" ride might be the lever action shocks used in 1947. Modern tubular shocks were not introduced on these trucks until 1950. I have both, a 1947 and a 1953, and my '53 rides much smoother, even with 16" bias tires.

http://s1291.photobucket.com/user/RdLessTaken/library/RdLessTaken%20Trucks