Yes, early models have the tracer cut option, or they can buy the EP26. Some may want to leave their factory one intact to throw it in the parts bin, that’s the only reason I mention the 26 as an option for purchase. I have a tendency to want to leave stock parts alone and save them just in case plans change down the road, but I change my mind a lot so that’s why I leave those options open.
Definitely don’t know who started the 27, I think it came from companies saying it would fit. I try to combat that every chance I get. I also see people try to run the 26 in the later models and that isn’t correct either and it doesn’t work right - causes plenty of confusion and I try to combat that as well when I see it.