MikeE,
The two radios you have are as follows..
#2864767 model # 251 is 68-9 Belvedere
#2864515 model # 244 is 68-9 Barracuda

Of course the model # 251 is correct for your
R line Belvedere, Road Runner, Satellite GTX models. The other radio you have should be noticably different, unless someone has monkied with it. The Barracuda radio will have a different chrome bezel, dial face, clear lense,
big fat chrome preset buttons, and the mounting stud will be on the bottom instead of the back,
those are a few of the more obvious differences.
If you have any other radio related questions, please feel free to contact us. Mopar radio restorations is what we specialize in..
Also if you go to our website, click on "services"
and you can see the difference between the model 251 and model 244.
Greg


Wards Classic Car Radio Repair Specializing in restoration and sales of Mopar A B E body radios
http://www.wardsclassiccarradiorepair.com/
gregward@mchsi.com