Never done the diode mod to this chassis sonoma.I have tried the diode mods to a few and I use a different resister than what you have listed but it in in the same area you have noted. what you have listed should work just fine.
ROBB I do not care for the resister diode mod myself. that is why I did not post the location I tried years ago. I have tried it on the 148 radios and it gives more swing. only problem is it gives too much audio. it works about like the R264 and R238 mods to the galaxy radios. I was replying to the ssb radio diode install that was posted on the 1st page. I would have to hunt up the 148 which I tried it on the resister by the audio transformer.
R228 for the 148 is what I tried the diode mod in that location.
Way off topic here
Reading through the thread and seeing Sonoma was taking part made think he hasn't been around in a bit. Anyone heard from him