The Pennsylvania Railroad Class 2D-F8 50-ton freight truck was originally manufactured in the 1920's with a riveted bolster. A version with a cast steel bolster was introduced in the 1930's. This type of truck was in faithful service for more than fifty years.
Bowser makes the only 2D-F8 in N scale. It is the later cast steel version, although I'm told that it's somewhat inaccurate (insofar as it lacks a spring plank) -
Bowser - wheelbase 10.43mm, frame width 16.61mm, wheel size 33", axle length 13.92mm