I am guessing this is your 1987 300D, arctic white/palomino--220k miles.
Chassis 124.133
Engine 603.960 I6
Model 300D Turbo

The crack is caused by thinning metal and deflection stress from the differential.
In plain English:
Junk the sub-frame and get another.
we have several members who go to the U-Pick salvage yards, and will look for what you need.
Look through the parts forum.



Have a great day.

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1985 300SD
1983 300D

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