or the new modified version with re-worked software to utilize 2nd prime in the normal upshift and renaming it a "6" speed.
Ok well I don't actually know this for a fact as I haven't driven a truck with the "new" "6 speed" transmission, but transengineer (who designs them) IIRC told me it also does not use 2nd prime in normal upshifting. I'm pretty sure(there is a small doubt as I have a terrible memory lol) that he said it is literally 100% identical in every way to the 545rfe, they just changed the name is all.
So basically people have been saying things like "I like the older 545rfe better than this new 6 speed" and stuff like that, when it is actually identical, even the way it shifts and doesn't use 2nd prime in normal upshifts.
Again, I'm not positive but if the guy that designs it says so then I'll believe it...