I have for sale a pair of the rare "flower bolts" that were used in W124 models to secure the inner firewall (behind the engine) together. These flower bolts are often missing or broken, or messed up because of engine heat back there.
These can be difficult to find in the EPC, but the MB part number is 124 821 00 73.
$8 postage-paid for both flower bolts. If you have a 124, these are a good set of spares to have.
Here is an image (borrowed from the Make-meister) of an .036 firewall with one flower-bolt installed, and the other missing.