No need to use a torrent, the latest gmap folder is available in the link for NA 2016.10 immediately above in my previous post. The PC Install is available from Post #1 there, 11 rar parts from ZippyShare can be simultaneously downloaded quickly and safely, then extract the rar files to find 'City Navigator North America NT 2016.10.gmap' unlock that and place it according to your OS [refer to the Maps downloading hints thread again]. Hook up your 376C and choose the parts of the US you want with MI, all quite easy and more importantly it's reliable as you know what you're getting. You don't have to only load large swathes like Western, Central or Eastern US [we're talking about MapInstall, not MapUpdater. You can send just a few tiles if you want or right up to the size limit MI advises is available on your datacard.

The method you're referring to ['install these .img files'], involves reverse-engineering the img file with [Only registered and activated users can see links. ] to make a simple preview map for install to PC for basic use on the PC itself only. It's pointless to then use that 'installed map data' to generate another image. It will not have search functions as you've read, and that's because there's no MDR data in a map installed like that. Forget about it. Another military saying appropriate if you did that: SNAFU. 'Cos that'd be the result.

About your original assumption that it would be copy/paste like a nuvi to place a map img on the 376C. The two types of device are like apples and oranges comparatively, 'old-school' devices like your plotter don't have a visible file system like modern devices as you know. All data, be that mapping voices or whatever is flashed to various 'regions' of the internal memory. In yours, the only map on the internal memory is the basemap afaik, that's in region 3 [0x03]. The only detail map is on the datacard and although it's removable media it's treated like another 'region', region 10 [0x0A]. Those old units don't have a separate preboot mode like nuvis either, they're perpetually in a kind of pseudo preboot which is why they can be flashed with Updater.exe but not updated via GarminExpress which requires MSM connection.