I think an email to VDO may be needed to get the resistance/pressure curves for the different senders.

The only info I have found so far is that the resistance ranges up to about 180 ohms at higher pressure. If you know what your fuel/oil pressure is, say, at idle, it could then be worth having a play with various different resistors to replicate the sender (connect a resistor between the appropriate monitor wire and earth) until the monitor gives close-on to the reading you'd expect ie if at idle your fuel pressure is 60psi, and a resistor of 150 ohms gives a reading of 60 psi on the monitor, it's just a case then of comparing this resistance value to the different sender curves to select the closest one.

If anyone knows the correct sender, or can think of a better/easier way than this, spill the beans.