I'm on a mission!
1147412037 is the Mercedes part # for the Mono-Valve (that controls coolant flow to the heater core in the passenger compartment).
1990 300D 2.5 turbo
[known in parts of Europe and Asia as a 250D 2.5 turbo].
'Roughly $150.00 U.S.D.
1147213007 is the Mercedes part # number for...