I just did this on my 450 SL. My DIY skills are middlin' at best, and this was more or less the worst job I've actually done on my car. I absolutely had to pull the radiator - there's not enough room to start with, and you need every bit. Next loosen the belts, unbolt the high/low side pipes at the power steering pump, then crack the pipes to get wiggle room (make sure the refrigerant's been evacuated of course), get under the car and unhook the pipes from the compressor, unbolt the compressor carrier, pull the compressor (it came out separately from the carrier) then reverse to get the new monster in. Extremely tight in there, extremely difficult to get leverage. I needed a wide assortment of swivel head ratchets and extensions to get the critter out (bad) and back in (worse). I finally went and used a lift, otherwise I'm not sure I would had made it. Took me something like 16 hours total. Drier was easy, didn't do expansion value. Of course, we have different engines, so I'm not sure if all of this applies to your situation. Good Luck!

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Tjohn

82 300 SD
77 450 SL (gone)