The elbows are the same. I'm not sure when the change over may have been for the PA on whether or not it has the lower elbow, or just needs the O-ring. I ran into the same problem at Advance locally. However, Autozone and PepBoys both carry them, as Bill mentioned, in the Dorman "Help" cards section.
This image shows the older tensioner assembly that uses an o-ring for the connection to the water pump and a plastic elbow for the connection to the LIM. The lower o-ring seals the return line from the heater core (the lower of the two heater hose connections). The joint is at the 7:00 O'Clock position relative to the black plastic pulley on the tensioner assembly.