I'd forgo the R4 compressor, I have a low mileage 79 300d, I first resealed the original compressor and it leaked around the can. I then bought a rebuilt R4 and it leaks a small amount of oil on an off also from around the can. I charged with Enviorsafe both times and the high side pressure does not exceed 215psi. It cools well but the oil leak is a problem waiting to happen. I'm going to convert to a Sanden compressor.

Tim