The most recent gmail on v23 wouldn't install via Google play (one included with v23)...
However this worked for me
Stop gmail clear/delete user data via app settings
Uninstall gmail via TB.
Try to install gmail again via play. . .doesn't install. .
Reboot. . .
Install gmail from play ... worked this time. . .
You can maybe skip the install try before reboot. .. that is just the sequence of steps I used. .. .
That same basic process has worked for me a few times for other Google apps that would not install via market on older rr versions.
As i said this didnt work for maps 6.5 but v23 came with it. . .
Ymmv..not responsible for bricks. . .etc
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