Easy to find the 722.3 in 1986-1988 W124, C124, S124.
All these models used mechanical speedo.
Internal gearing should be the same.
1= 3.68, 2= 2.41, 3=1.44, 4=1.0
They are all second gear start which isn't a problem if you use a rear gear ratio numerically above 3.0
I run the original stock 722.3 in my 1988 300CE low boost twin turbo M103-12V which has dyno'd at close to 400BHP.
No problems handling the power.

Ed A.

__________________
http://i19.photobucket.com/albums/b1...c/GOWIDE-1.jpg
1971 280SL ROADSTER
1988 300CE TWIN TURBO WIDEBODY
1994 E320 CABRIOLET
1999 C43 AMG
2005 G55K AMG
2008 CLK63 AMG BLACK SERIES