OP
Okay, I don't know the K-frames as well as so many of you. Let me just say that I have never seen a 6-inch Model 15 and I have never heard of nor dreamt about an 8-3/8" Model 15.
I can't really even figure out why either would exist when the Model 14 clearly covers that territory and does it with grace.
Sevens,
It's good to see you on the round side of the world, rather than just on the back and forth side.
I'm no K frame expert, but you are correct, Model 14's are classically 6" while Model 15's are classically 4". I have seen some 8 3/8" 14's before, but had never seen an 8 3/8" 15 before that day - one of the reasons I was looking at it so closely. (It also had fabulous wood on it).
Oddities are what makes this all so fun.