In case someone is looking for the same answer as I did a couple of weeks ago: I was looking for a new bezel insert for a mod on a SNZH55, but couldn't find the right one amongst the inserts specifically marked for the SNZH. Then I read somewhere that the insert for the Turtle would also fit, but somehow it was never really confirmed etc. etc. So in the end I just bought an Insert from dr.seikostain on ebay described as "Made to fit standard & aftermarket bezels for : SEIKO NEW TURTLE SRP 772,774,775,777,777..ETC".
I really liked the looks of it and I really wanted it for the mod, so I got it.
And it fits perfectly! Same size, same diameters (39.5mm OD/ 32.5mm ID), I love it.