Operating Era: 1895-1925. Pennsylvania RR. The GG class was the first hopper-bottom car on the railroad. The design set the mark not only for Pennsy but all railroads for the next decade. Almost 2,800 cars were built beginning in 1895 and as late as 1902. Most cars were 4'8" tall inside but a new design for a 5'11" car was built in 1898. Early cars had 5' wheelbase 35-ton trucks. The cars were found to be strong enough to support more weight when heavier capacity trucks were used. Most cars received 5'6" wheelbase 50- ton trucks by 1909. At that time many cars were rebuilt to the 5'11" height by adding another board to the top of the car. In the late 'teens the cars were given safety appliances. Cars that survived into the 1920s certainly had them. All cars were gone by 1926.