I've abandoned upgrading my '87300TD brakes and
have an exc cond used GIRLING double-diaphram
Brake Booster. It came from a known 400E w/60Kmi
car & has been stored in a heated basement f/7yrs.
It's an essential part if you're adding larger calipers
to your W124. I'm told it's also compatable w/210,
but have no confimation on this. $50. takes it,
shipping included. Will Rhyins.nyc10009@gmail.com Tel: (646) 318-8246.