6k on mine. P.O replaced it for some reason I don't remember. 128k on the car.

242,000 on the timing chain .The last 100,000 or so are mine...it's on the short list.

The camshaft sprocket is twice the diameter of the crank sprocket, with the same tooth pitch.

That means that if you are running an elongated chain, the camshaft sprocket will wear at twice the rate of the crank sprocket as twice as much total elongation will be seen on the cam sprocket compared to the crank sprocket.

If your cam sprocket is fine, the crank sprocket is almost certainly good as well. If your cam sprocket is "shark-toothed," the crank sprocket probably is too, to half the amount.

204k on mine in the 92. should have left it on, had it changed and the thing still runs like all kinds of fecal matter!

I do not understand this one. I believe the Crankshaft Sprocket has less teeth to spread the load over (to do the work) and has the entire load of driving the Camshaft, IP and Vacuum Pump (by way of the Pump Timer). And, the friction of the Chain Tensioner on the chain (that long rail).
I would expect the Crankshaft Gear to have the most wear on it (if the timing gears are made of the same material).

The reason that the teeth suffer undue wear is the fact that the first three or four teeth do all the work. The remainder of the teeth...........depending on the severity of the elongation..........are just coming along for the ride.

So, with only three or four teeth pulling all the load, the wear is increased significantly on those teeth. Naturally, the first three or four teeth is relative to the approach of the chain and they are changing constantly.

It can be argued that the crankshaft will suffer from greater wear in the sprocket because the teeth see the chain once per engine revolution where the teeth on the camshaft see the chain once per every two engine revolutions.

That's a good point. I guess things are just going to wear out and that's the way it is. Trying to make these old engines last 1M miles or the rest of a person's life is probably possible but it'd be cheaper just to junk it when it blows. Sad as it is :(. Nothing lasts forever. But on the other hand, w123's were some of the best cars made, they're easy to work on, and just a great bare bones diesel engine. So in that case, it just depends on how crazy the owner is about their vehicle, or maybe just crazy. Lol. Sometimes I wonder why I nickel and dime a piece at a time on my cars. But it's a very good piece of equipment. May as well keep up with the small stuff.