Bob,
These cars came with a variety of numbers. Chasis #, Body #, engine #, stering box, trans, rear end and even a number for the the right and left front axle assembles.

If you don't already have a copy of the MB service manual model 190 get one (they appear on ebay frequently). page VI and VII
show where these numbers are. Also the spare parts manual (glove box book} shows the number locations on page 5 and 6.

Stamped into the fire wall is the car's body number not to be confused witht he chasis number (yes they are usually different). You'll also find your chasis # stamped into the frame on the passenger side down by the voltage regulator. There is also a plate they attach in that area that has the chasis # on it.

Engine number is found on a plate attached to drivers side of the engine. I can't remember is they stamped that number into the block or not but t sure seems like they did.