I did this to one of my old Grants. It works great! I had to adjust the 1uf up a bit and added a pot and diode where R131 would be, I just followed the silk screen and ended up with a great working limiter.MKwrench,
those are all good changes, but there is a better mod for the audio.
try changing the value of R228 to 1.2K and then adding a 1uf non polarized cap from pin 9 of the audio chip to the junction of R194/R228/D36.
Leave the limiter intact and on the versions that have a fixed value instead of an AMC pot you'll have to change that 10K resistor to a variable pot.
now adjust the AMC using the scope to get the negative peaks just under 100%.
note, this mod only really does anything if you are lowering the deadkey of the radio and want to maintain max swing without clipping the negative peaks.
all credit for this mod goes to Exit13.
LC
I noticed .that more uf = more sensitivity for swing.