It took forever to get to this project, but it's a very simple swap. The speedo gear is mounted to the rear most disc in the transmission. This disc is notched and is part of the park mechanism. I swapped over that disc, and the tube that feeds lubricant to the speedo drive gear, and bolted the new housing in place. The case is exactly the same, so everything bolted up easily.

The engine and tranny are going back in the this weekend. i'll post an update again when the car is back on the road.

BTW, I read the transmission number incorrectly. The w124 transmission is a 722.369 not a 722.389 as I originally stated.