I don't know if/when MB will ever sell a "single-source" technical manual for a 140 chassis. The info is really spread out in different areas, even in the dealer shops. The area where the most info can be found is in the WIS computer. (Workstation Information System). This is done on a subscription service and is PC based.
But even WIS doesn't have everything for it. Other good sources are the DM's (diagnostic manuals) but these are sorted by systems, not by chassis number, so would be buying lots and lots of info that won't pertain to your car.
There are electrical diagram books (ETM, Electrical Troubleshooting Manual) which are chassis-specific.
I would think that shortly (if it hasn't happened already) that the aftermarket would provide a few good manuals for the 140 chassis.