I was thinking the 115' still had the external regulator , your signaoure says 1975 so here's the most likely one :

MERCEDES-BENZ 230 1974-1978
MERCEDES-BENZ 240D 1974-1983
MERCEDES-BENZ 280 1973-1976
MERCEDES-BENZ 280C 1973-1976
MERCEDES-BENZ 280CE 1978-1981
MERCEDES-BENZ 280E 1977-1981
MERCEDES-BENZ 280S 1975-1976
MERCEDES-BENZ 280SE 1977-1980
MERCEDES-BENZ 300CD 1978-1985
MERCEDES-BENZ 300D 1975-1985
MERCEDES-BENZ 300SD 1978-1985
MERCEDES-BENZ 300TD 1979-1985
MERCEDES-BENZ 450SE 1973-1976
MERCEDES-BENZ 450SEL 1973-1980
MERCEDES-BENZ 450SL 1974-1980
MERCEDES-BENZ 450SLC 1974-1980

This is the 55 ampere one with internal regulator, if the bearings are bad it trash, order in the 65 ampere one for a 1985 300D, it'll bolt right up and have more out put .

Be aware that the brand of the regulator has everything to do with the charging voltage.

I only use BOSCH branded regulators for this reason .

__________________
-Nate
1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better