CSX, "COKE EXPRESS" ?

[thirdrail1]

These cars were specifically built to move coke from coking plants to steel mills. Some of this traffic moved in short unit trains, hence the "Coke Express" slogan. Coke is lighter than the coal from which it is made, hence the higher sides on these cars to haul the equivalent amount of weight.

[Anonymous]

Saw a train waiting on a sidind near Elberton , Georgia, on the Atlanta-Abbeville line, and it had a open hopper car, just one, in a long mixed freight train, that was a lot shorter than a normal coal hopper, and 2-3 feet taller than a normal coal hopper, it was black with the usual CSX markings and numbers in yellow, but across the top in big italic yellow letters , it read
C O K E E X P R E S S.
Whats up with theses cars?
Thanks in advance.