When you get the regulator make sure you get the correct side, right or left. As far as Wxxx that is the chassis designation basically. So you are fine with that. There is a chart somewhere that explains what is what. My car is a C230 which is a W202 for example. It is lingo you will see a lot on this site and others.

Mike

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1998 C230 330,000 miles (currently dead of second failed EIS, yours will fail too, turning you into the dealer's personal human cash machine)
1988 F150 144,000 miles (leaks all the colors of the rainbow)
Previous stars: 1981 Brava 210,000 miles, 1978 128 150,000 miles, 1977 B200 Van 175,000 miles, 1972 Vega (great, if rusty, car), 1972 Celica, 1986.5 Supra