What year engine?
It was said years ago by Mercruiser instructors that the frequency readings were different and it's best to just use one of theirs to ensure the correct parts are used. But that probably was mostly just a ploy as the difference appears to be very little.
The sensor itself rarely seems to fail.
For a more in-depth version of this though, Searching online suggests that the old GM designed sensor frequency is 10.5 kHz which may be the same as Mercruisers but I can't say for sure.... The newer designed sensors found on both GM and Mercruiser seems to have a wider range of frequency but again it's supposed to be all tuned at the factory when adjusting frequencies. Mercruiser had a separate module back in the 90's but I believe so did the GM trucks.( < Just looked and the GM trucks had the same design module but not sure of the frequency numbers if any)... The newer designed knock system is tuned/controlled within the ECM vs a separate module.
Within the links below you'll see some numbers on the side of the sensor which seems to suggest the numbers represent the frequency levels. If so, and you can see some numbers on the original sensor you have or search the Mercruiser part number sensor online/EBay to see if you can find some numbers on a true Mercruiser sensor to see if the numbers in the photos match then it may help you be more confident that a GM sensor may work exactly the same as an OEM Merc sensor.
For good info regarding tuning/adjusting frequencies, I found these four links interesting in trying to help answer this question for you,
https://forums.holley.com/showthread.php?2534-Connecting-amp-Tuning-Knock-Sensors-Holley-EFI
http://mtg-technologies.com/automotivesubpages/knock/GM10456288.htm
http://delphi.com/manufacturers/aut...sion/diesel-and-gasoline/flat-response-knock/
Knock (Detonation) Sensors - | Standard Notice the GM sensor number is GMKS6.
Further searching, It seems there are two GM sensor part numbers of the old design, GM # 10456287 & 10456288 See list below,
http://www.binderplanet.com/forums/index.php?threads/parts-needed-for-the-gm-conversion.45292/
Options: Programming chip may be required to prevent SES light if not used.
1. Knock sensor- Screws into the side of the engine in front of the starter. It screws into the water drain plug hole. Get from donor.
If you are not going to program the chip then I recommend you run the knock and ESC.
Here's a short list of knock sensors and ESC's
ESC Module(GM #)..Knock Sensor(GM #) ..Known Applications
16052391 .............10456287 .................5.0L V8
16052401 .............10456288 .................5.7L V8
16128261 .............10456288 .................5.7L V8
16065711 .............10456288 .................4.3L V6, 5.7L V8
16128251 .............10456288 .................4.3L V6, 5.7L V8
16131171 .............10456288 .................7.4L V8
2
. Knock control- ESC-electronic spark control. this sends the signal from the Knock sensor to the ECM to reduce the timing if it hears a ping.
