The alternator on my 1990 350SDL 205,000 miles has the whirring sound of impending doom. It has a plug in from the harness yet all replacement show
the spade nut connections. Please advise

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1990 350 SDL
Currently: 180,000 miles
Factory rebuilt bottom end rods, bearings and head gasket @ 75,000 in 1997

GJEMD My friend you might not have given the right information on your engine type and model .I checked it out and the right alternator for your engine going off your information is Bosch AL 66X and it is as you say they do have spade fixings with nut and washer 2 connections . So what numbers do you find on the one you removed . You car might have had a new wiring loom fitted .

My '91 350SD with build date of 10/90 has the updated style alternator with the ring terminals instead of the older plug. Someone may have hacked your harness for the old style alternator.

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Current stable:
1995 E320 149K (Nancy)
1983 500SL 120K (SLoL)

Black Sheep:
1985 524TD 167K (TotalDumpster™)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

Thanks to all. I was confusing the plug for the voltage regulator and the harness connections. THe plug-in Bosch is a 70 amp unit. You're all correct the Diesels require the 80 amp AL 66X. I've owned my 350 for 25 of it's 29 years and I must say 29 years and 205,000 not bad service for the factory alternator.

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1990 350 SDL
Currently: 180,000 miles
Factory rebuilt bottom end rods, bearings and head gasket @ 75,000 in 1997