The reason for the 1996 and on date has to do with the accessability of the prom.
There are three ways to do this programming. The first is the hook an adapter right to the prom while its in the circuit. This requires disassembly and wouldn't be doable with MB scanner.
The second way is to hook right to the electrical connector at the back of the cluster. This also isn't likely to be a shop operation.
The last way is to program through the data line (CAN). The level of this activity varies in the different models but almost all were hooked up by 1996. This ability should be available with the HHT or Star.
We are able to do this to new Volvo and VW/Audi speedos with our Factory scanners for each. Volvo speedos can only be done for the first 100-150 miles (?? I think). VW/Audi I think can always be set forward (not back). All this of course has to do with the tool software. These tools that I linked (which we are contemplating) aren't so restricted.
BTW the rumor has it that MB has two counters within their chip; one accessable with data stream the other not. The second is said to be for security. Also I am not sure on MB but on BMW the odo value is kept by more than one controller and if you have them out of sync the systems go "limp home mode"
[This message has been edited by stevebfl (edited 03-18-2000).]