I am sorry to ask off topic question.

Does W124 also have BTDC?

Alldata document does not mention it:

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The engine must be checked for correct basic timing (crankshaft at 0 °TDC and camshaft at TDC mark) to determine if the timing chain is stretched.

In order to check basic engine timing, turn the engine slowly (in normal rotation) using the crankshaft pulley bolt until the mark on camshaft sprocket aligns with the mark on the camshaft bearing cap (arrows, Figure 1). The position of the crankshaft will tell if the chain is stretched, i.e. is still within specifications (Figure 2). For engine 606, refer to SMS Job No. AR 05.20-6010 HA.

1. If the timing mark on the crankshaft pulley is off by 3 °- 10 °:

^ The timing chain is stretched and should be replaced (Engine 602/603 SMS, Job No. 05.10-320; Engine 606 SMS, Job No. AR05.10-7601 HA).
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1992 300D 2.5 turbo diesel. 319 k miles.
124.128 chassis, 602.962 engine, 722.418 tranny.