I'm finally going to do the differential upgrade on my E420. I found a great source for my differential, only $470 delivered. It's from a 1992 500SL with only 50k miles (I know - it's only a 2.65 instead of a 2.82, but I'm a wuss).

Now I need to find a black box to correct the signal to my speedometer. Does anyone have a source for this, and more importantly, any instructions for doing it?

Thanks,
Troy K.
1994 E420 84k

Man!

I did this MANY years ago for my VW when I swapped the OEM speedo for a big AutoMeter unit.

I don't have the detailed info anymore but they were called "California Speedometers". I can't recall if you still have the mechanical or electrical setup on yours, but mine (of course) was mechanical. All I had to do was tell them the speed reduction/acceleration ratio and mark the portion of the cable that I sent to them to have the "black box" installed.

The ratio info in your case would be the difference between the gearing on the the diif swap...in mine, I had to figure out (based on the manufacturers specs of the new speedo) what the offset was for accurate readings...

__________________
2009 ML350 (106K) - Family vehicle
2001 CLK430 Cabriolet (80K) - Wife's car
2005 BMW 645CI (138K) - My daily driver
2016 Mustang (32K) - Daughter's car

I'm almost 100% positive that this is an electronic speedo. Others that have done the differential swap have talked about an electronic speedo correction bos, but I don't know where to order one from or how to install it.

Any help from the differential swap club would be much appreciated.

Troy K.
1995 E420 84k