Both are pin-to-pin compatible and have very little differences. You can replace a 4192 with a 4191 without any worries.
The only difference is in THD rating which depends on the mark like mark II, V, X etc and minor changes in the internal circuitry and supply voltage leves (4191 -53v against 4192 -52.5).
The 4192 should have a voltage on pin 12 similar to that on pin 11. They may even be joined on the PCB. These are the main supplies to the amp so around 35 to 50 volts depending on what the map runs on,