Jim, I don't understand why you want to change from bullet proof compresors to the higher failure rate newer style compressors. The A6 on your 3.5 is about the most durable compressor you can get. The only reason car mfgs quit using them is, because they weigh as much as a small Japanese engine. The York compressor on your 280SL is also an excellent compressor. I would buy a new one and not rebuilt. If you get a rebuilt from say Sedona or Phoenix, the metal in the rods and pistons is pretty well fatigued. I can't remember what's in the 6.3, but I think it's a York. I'd also stick with R-12.

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