Parts needed to replace AC compressor?

I'm buying the parts to have my ac compressor replaced, however I'm not entirely sure what all I need. I'm seeing from different sources that I also need to get in addition to the compressor itself, the ac compressor expansion valve and receiver drier desiccant element, but from other sources I'm seeing that I need the ac expansion valve and the receiver drier accumulator, but no mention of the desiccant element. I'm hoping someone can chime in and tell me exactly what I need in order to replace the ac compressor successfully to prevent future failures.