John - The numbers he's looking for are not stamped or cast into the housing of that differential case; they're not quite like any such numbers he's ever seen on car parts, making them harder to find under there. These ratio numbers were added during or just after assembly as a notation of just which gear set had been installed inside. As such, they were scribed into the metal of the case by hand and are thinner, fainter and much more like graceful, flowing handwriting than what he's used to seeing. So, that said by way of forewarning, here's how and where to look:
Under the car at the left rear near the tire, with the axle housing on your left and looking toward the center of the car, the left side of the differential housing is your view of the moment. It will not look so much like one of our Detroit "pumpkins", largely because of the straight, horizontal nature of its lower edge area. There is a straight, smooth, 1/2 inch wide raised area perhaps a foot long running from back to front along or near the bottom edge of the German 'punkin', and this is where the magic numbers reside, toward the rear. (There should be other numbers nearer the front extreme of this area; they are not relevant to your quest.) So, for your purpose, the rearmost 30% or so of the smooth, straight area will probably need to be cleaned of whatever encrusted grease and road schmutz has accumulated.
Maybe a couple of light passes with something like a butterknife, if you're lucky -- certainly not to move any metal. And/or a shop rag --solvent optional as appropriate-- followed up with a hand-light applied from the sides (to highlight) as well as directly. He's looking for a group of three handwritten, graceful, rather delicate numbers. There is a comma separating the first one from the other two -- following the European custom of using a comma to indicate the decimal -- unless it's just not legible any more. These numbers nearly fill the 1/2 inch height of the area, making them larger as well as fainter than what he's used to seeing. Unless your vendor has ever been down this path before, he'd be up a creek--without a steam cleaner and maybe a magnifying glass. But with a forewarned and focused approach, there they'll be. Good hunting!
Denny
