After reading thread here seems I would need to reflash 37xx logo if I converted to 34xx and wanted to go back to 37xx.
So using 37xx boot.bin (extracted from GUPDATE.GCD version 4.6), I did following to create a rgn file to allow return to 3790 logo.
Opened Region Tool (84) and loaded boot.bin (from 37xx 460 version) then loaded logo.bin (37xx from turboccc post on how to change logo) then saved file as 37xx_460_logo_hid1101.rgn.

Surprised to see that the logo.bin file size for 37xx in RgnTool was 3145728 compared to only 10281 for 34xx logo bin. Does this sound right or did I screw up logo somehow?