I checked out Hermon's link... and I'd NEVER question Charlie's input on anything...
there I was scratching my head...then I read closer...he listed the "TRADITIONAL" GTs.
I've been what I call "Over-footing" my lighter walled GTs for a long time with 2117 and they're just fine... bit of hot melt or epoxy, then the insert and slide the over footing down to touch the slight collar on the heavier insert (I use the brass ones) and let them set up.
HOWEVER, I use the plain BLACK shaft... ergo, the difference in Charlie's listing... the 2117 fit my 5575's beautifully, but he TRADITIONAL have that coating on to look wood grained... More weight, thicker OD... but the plain
black 5575 wear the 2117 well. Getting the nice long taper on the back to ride up over the pivot point on my shelf was key for me... a smaller taper worked ok on the front behind the insert.
FWIW...