The SRT kit for the P239 is either long gone of really dearly priced these days. In looking at the parts included it looks to me like the SRT Sear (1200457R) and the SRT Safety Lever (Lever-9) are the only parts in the kit, is that correct?

And the trigger bar return spring.

The trigger bar return spring aft end that catches in the trigger bar notch has to be shortened approximately .040" so it does not interfere with the long fingered SRT firing pin safety lever.

DA/SA SRT sear & safety bars are the same.

I just installed two P239 SRTs today. I used P226, P229, etc. kits and I ordered what I thought were the appropriate return springs but they ended up being the same as the original. I just used a pair of small snips and took off a little. Worked like a charm.