Ok, just discovered part of my problem is there are 2 part numbers on the back - I was only searching for the first one:

1 E1 00 10 059
and
1 e1 02*10 059

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1991 300E 124.030 103.983KE 722358 03 412178
207K

1979 240D 123.123 250K (Project car)

2000 Ford Ranger, 187K

2015 Dodge Ram 1500 EcoDiesel 37K

And many, if not all the ones on ebay have 51 instead of 59.

But is 51 a good substitute for 59?

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1991 300E 124.030 103.983KE 722358 03 412178
207K

1979 240D 123.123 250K (Project car)

2000 Ford Ranger, 187K

2015 Dodge Ram 1500 EcoDiesel 37K

Bumping this, still searching for a replacement.

__________________
1991 300E 124.030 103.983KE 722358 03 412178
207K

1979 240D 123.123 250K (Project car)

2000 Ford Ranger, 187K

2015 Dodge Ram 1500 EcoDiesel 37K

AFAIK they are still available new from the dealer and aren't really very expensive.

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90 300TE 4-M
Turbo 103, T3/T04E 50 trim
T04B cover .60 AR
Stage 3 turbine .63 AR
A2W I/C, 40 LB/HR
MS2E, 60-2 Direct Coil Control
3" Exh, AEM W/B O2
Underdrive Alt. and P/S Pulleys,
Vented Rear Discs, .034 Booster.
3.07 diffs 1st Gear Start

90 300CE 104.980
Milled & ported head, 10.3:1 compression
197° intake cam w/20° advancer
Tuned CIS ECU
4° ignition advance
PCS TCM2000, built 722.6
600W networked suction fan
Sportline sway bars
V8 rear subframe, Quaife ATB 3.06 diff

The OEM MB inside/interior mirror for your model came back as discontinued and is no longer available. Here's a web page confirming the mirror is discontinued https://www.mbpartsprime.com/parts-list/1991-mercedes-300e-2_6-6_cyl_2_6_l_gas/glass_windshield.html