Believe it or not, did you try the J.C.Whitney Catalog?
Around 4 years ago, I purchased transmission repairs manuals from them
for the Mercedes 722.1, 722.2 (one book) and the 722.2, 722.4 (2nd
According to the second volume, the 722.3 and 722.4
(W4A 040) transmissions were introduced in late 1980. Thus that
probably includes your car.
These manuals are published by the:
Automatic Transmission Service Group
9200 South Dadeland Blvd. Suite 114
Miami, Fl 33156
Apparently they cater to the independant transmission repair shops.
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