BUT on Boschs the brushes are an integral part of the Regulator.

Reliable Sources (US WEST COAST Family of Re-builders) say Bosch Brush materiel is "Hard"
so always check the "Slip Rings" for excessive wear...
"Slip Rings" are the rotating connection between the Rotor and the Brushes
that the Brushes "Ride" on.

Rebuilding is hit or miss from all the Big Box suppliers.
"Spray and Pray" is the actual rebuilding process.
AND your Alt mos likely Vacationed temporarily in
"Old Mexico" during the process.

Me... I'd go GSXR's 143/150 Amp upgrade route (As I have)
It'd require rewiring the Alt's conductors to a Larger Diameter Wiring.

If you look at the cost of a New Mercedes V.R. as opposed to a Reman Alt,
You'll be all over the "Replace the Voltage Regulator" Bandwagon.

New Regulator is 65 bucks
Re-Man Alt from MB is 306 bucks

URRGHK!

Bosch Reman from "Car House" next to Nevada of AL65X 70Amp is $185.00
With 2 yr warranty and roadside assist.

BUT!
Per your original Inquiry You DO Need At Least a New Regulator.

Your MB Your Pleasure.

__________________
'84 300SD sold
124.128