OM648 swap into a w123
OM648 swap into a w123
Maybe you can get an ABS-controlunit to send the speed signals via canbus by just feeding it with 4 (or maybe less) rectangular signals on the speed sensor input wires. It will throw some errors, but I guess it will read the correct speed and prevent the ECU from going into limp mode. Maybe even the automatic transmission will work just with this.