Here is what the GACUtil app tells me;
C:\Program Files (x86)\Microsoft...10.0\VC>gacutil.exe /l System.ServiceModel.Activation
Microsoft (R) .NET Global Assembly Cache Utility. Version 4.0.30319.1
Copyright (c) Microsoft Corporation. All rights reserved.
The Global Assembly Cache contains the following assemblies:
System.ServiceModel.Activation, Version=220.127.116.11, Culture=neutral, PublicKeyTok
Number of items = 1
The error I get when trying to install the WebAPI.all NuGet package;
Install failed. Rolling back...
Failed to add reference to 'System.ServiceModel.Activation'. Please make sure that it is in the Global Assembly Cache.
No version information is presented, thus I can't compare what's in my GAC to what the NuGet package wants/expects.