How to identify A/C compressor number

[krasnit]

Hi:
Last week my A/C stopped working. It seems the R134 has leaked out from the compressor shaft between the clutch and the body of the compressor, as there is the green dye visible as having emanating from that area. The seals probably popped. Not sure why except that it got cool up north here and I started to use the heater for a few days.

It looks like I will need a new compressor, unless there is a rebuild kit somehwhere on the market, which I do not know of.

How does one determine which part number it is without taking it out first, as the 300e 1991 model could use one of two replacement compressors, the Nippon Denso 10P15C or 10P17C?

Thanks,
Ted