1373 is the External Exhaust version with a blower type fan that pushes exhaust air through the card and outside through the rear of the case.
1372 is a more effective and quieter cooler, but it blows directly onto the GPU and pushes hot exhaust air into the inside of the case.
The External Exhaust will keep your case temperatures cooler, but the difference is not enough to make much, if any, difference to your system. You should get the 1372 for the quieter fan. Both are Superclocked models.