Maybe GPS FW is in some NVM region and it's only writen in FW, becouse when you convert from 37xx to 34xx GPS FW don't change.
Already google all for GPS FW, read all post on Noeman but can't find answer where is GPS FW.
Someone here on Noeman write about region 91 but don't know what is inside this region.

Do we have UAT FW of nuvi 37xx or 34xx?
Maybe there we can find answer.