The compressor on my 2013 silverado 2500hd ext cab 4wd has started leaking at the front seal. I am trying to get parts ordered so that I can repair it. ...

The compressor on my 2013 silverado 2500hd ext cab 4wd has started leaking at the front seal. I am trying to get parts ordered so that I can repair it. The compressor that is in there now is a Denso 10SE18F. I can find no compressors that have that exact model number, mostly they are 10S17F. Is just a portion of the model number applicable, or the whole thing?
Also, they are listed a w/Diode or W/O Diode. Where is this mysterious diode, so that I can tell if I have it or not?

Thanks,