Unsure if a "universal kit" exists. If you are lucky, the tag with part number is still on yours. If not, ask your friendly Dealership parts person what harness part number is and their best price. Alternatively, troll eBay or pick and pull yards. For one of mine, I got best price from the local dealer. Another came from Rusty at buymbparts 1-800-741-5252. If you go used, ensure that what you are looking at has a build date on it newer than (?, homework needed)) to ensure its an upgraded verson. I've seen ebay listings that skirt around the build date. I have one on ebay now, but its for a 95. Its build date is 2008.

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Hanno
'79 6.9 Sold (after 27 years)
'83 280SL, 5 spd.
'94 E320 Sdn. 5 spd conversion
'02 E320 Sdn.(on loan to mom!)
'87 300E (5 spd. conversion) Sold
'05 E500 Wagon

Thanks! I will try these and watch the dates. Looks like a common problem.

It's a dealer only item, very expensive, but why would you replace the wiring harness on a 92 300TE? Far from being a common failure, it's very uncommon, maybe unprecedented.