I was all ready to order a SRT for an older P220, but then noticed that Sig sells 2 kits: [1] sku: PKIT-SRT-226-227-229 for the P226/7/8/9 and then [2] sku: 220-SRT-PKIT for just the P220(?).

The P220 kit includes the sear, safety lever, AND decock lever, whereas the other kit (which costs the same) does not include the decock lever.

Is there something different about the P220 decock lever that would necessitate swapping it out?

I've installed several P220 SRT kits, never used the newer decocker lever with any of them and never had an issue. Since I have about six P220s and all either refinished or factory two-tone, the black decocker lever that comes with the SRT kits are useless to me.

Same here.

Was able to install the SRT kit in a newer stainless P220 as well as a 9mm P220 from 1976.

They both worked fine and didn't need the decocker for either one.

Thanks. I suspected as much, but I don't have as much experience with the P220. The different SRT kit options must be some weird Sigexeter thing.

Semi-related question.. Looking in my parts box, I noticed I've got 2 different styles of decock levers. Here's a pic. You'll notice the 'handles' have different profiles. Just curious, what's the story behind the 2 different styles?

I believe the one on the top is the new version. It has a small nub on the top. It contacts the frame in that location when the decocker is released. Maybe the original decocker tended to over rotate when it was released? I’m not really sure.

I believe the difference was for E Grips [the one piece grip]. A clearance issue with the grip.