I have for sale a chassis reinforcement plate for all .036 and .034 models. This is a specific item for the V-8 W124 models, and it is the plate that the transmission (rear) mount bolts to.
Ideal as a spare, as these do get lost. NLA from MB -- see attached image
MB part number 124 242 14 01.
$70 shipped -- $20 of that cost is shipping via USPS Priority Mail.