Windows NT 3.51 was significant in adding support for the PowerPC processor from IBM. Because this release was delayed for the PowerPC port, it was very stable when it came out as over a thousand bugs had been addressed in between 3.5 & 3.51 .
3.51 was released in May of 1995 right before the launch of Windows 95. This made NT 3.51 feel somewhat dated as it still retained the program manager/file manager feel to them, while in August Windows 95 would feature the new explorer shell.
However after the launch of Windows 95, there was work to port the new UI to Windows NT in the form of newshell.
Newshell only made it to Beta 2, and was never updated beyond that.
One cool feature of NT 3.51 is that it was supported by Office 95 & 97. Combined with the newshell beta it gave NT 3.51 the feeling of being more modern than the dated program manager feeling NT 3.1-3.51 …
Of my test programs, they all continue to run flawlessly. Even SQL Server 4.21 happily runs as a service on NT 3.51.
I figured it was worth doing a quick video of what the new shell experience was like on NT.
By this time NT was starting to look and feel like a dated system because of the reliance on Program manager. Of course we all knew it would be addressed in the next version of NT, Windows NT 4.0