No five speeds with six-cylinder engines in '87, but there are a few hundred '86 300Es with five-speeds; '86 300E five-speed were "on allocation" so dealers had to take them whether they wanted to or not, and they didn't like this arrangement because very few customers wanted five speeds, so MBNA relented in '87 and just cancelled the five-speed, but brought it back as a special order item for 124s and 201s with six-cylinder engines in 1988.

All use the same basic overdrive five speed, and the same axle ratio as auto trans versions of the same model. A DIY option for the 190E is the direct drive five speed from the 16V, but it requires the 16V driveshaft due to different transmission housing lengths and probably won't install in a W124 without a custom driveshaft length.

The overdrive five-speed was also available on sixes in later years, but however you cut it, they are rare.

Your best bet is to keep looking until you find a six-cylinder five speed in a junkyard, preferably from a W124. Take everything associated with the clutch, shift linkage, etc. and probably the driveshaft too. If in doubt about whether you need the part, take it.

Trying to adapt some other five-speed to a W124 would be a major engineering project unless you can find someone who has done it and documented everything needed for the conversion. I would not attempt it.

Duke