I found that I was still missing 70+ updates after downloading updates with wsusofflineupdater so I manually downloaded them from the update catalog and added them in. Powershell Script for slipstreaming updates (https://www.reddit.com/r/sysadmin/comments/4ak3h7/powershell_script_to_slipstream_windows_updates/) cls #This is the path to your latest DISM version. DISM 10 is required to slipstream Windows 10. $DISMPath = "C:\Program Files (x86)\Windows Kits\10\Assessment and Deployment Kit\Deployment Tools\amd64\DISM\DISM.exe" #This is any path that has enough hard disk space to mount the image and slipstream updates into it. $MountPath = “D:\TempMount\mount” #Update the paths below as necessary to point to your Windows Updates folders. $UpdatesPath1 = "D:\WU\wsusoffline105\wsusoffline\client\w61-x64\glb\*" $UpdatesPath2 = "D:\WU\wsusoffline105\wsusoffline\client\w63-x64\glb\*" $UpdatesPath3 = "D:\WU\wsusoffline105\wsusoffline\client\w100-x64\glb\*" #Update the paths below to point to your "install.wim" locations. $WimFile1 = “D:\DeploymentShare\Operating Systems\Windows 7 x64\sources\install.wim” $WimFile2 = “D:\DeploymentShare\Operating Systems\Windows 8.1 Enterprise x64\sources\install.wim” $WimFile3 = “D:\DeploymentShare\Operating Systems\Windows 10 Enterprise x64 1511\sources\install.wim” $WimFile4 = “D:\DeploymentShare\Operating Systems\Windows Server 2008 R2 x64\sources\install.wim” $WimFile5 = “D:\DeploymentShare\Operating Systems\Windows Server 2012 R2 SERVERSTANDARDCORE x64\sources\install.wim” Do { #Cleanup any existing images that may already be mounted. &$DISMPath /Cleanup-Wim #Prompt user for choice of OS or to exit. Write-Host "" Write-Host "Windows Update Slipstream into Deployment Files" Write-Host "1 - Windows 7 SP1 x64" Write-Host "2 - Windows 8.1 x64" Write-Host "3 - Windows 10 1511 x64" Write-Host "4 - Windows Server 2008 R2 SP1" Write-Host "5 - Windows Server 2012 R2" Write-Host "0 - Exit" $Choice = Read-Host -Prompt 'Select an Operating System to Update' #Based on user's input above, update the variables to select the correct image and update file path. If ($Choice -eq "1") { Write-Host "Please stand by, this can take a while depending on the number of updates." Write-Host "Slipstreaming updates to Windows 7 SP1 x64..." $WimFile = $WimFile1 $UpdatesPath = $UpdatesPath1 } elseif ($Choice -eq "2") { Write-Host "Please stand by, this can take a while depending on the number of updates." Write-Host "Slipstreaming updates to Windows 8.1 x64..." $WimFile = $WimFile2 $UpdatesPath = $UpdatesPath2 } elseif ($Choice -eq "3") { Write-Host "Please stand by, this can take a while depending on the number of updates." Write-Host "Slipstreaming updates to Windows 10 1511 x64..." $WimFile = $WimFile3 $UpdatesPath = $UpdatesPath3 } elseif ($Choice -eq "4") { Write-Host "Please stand by, this can take a while depending on the number of updates." Write-Host "Slipstreaming updates to Windows Server 2008 R2 SP1..." $WimFile = $WimFile4 $UpdatesPath = $UpdatesPath1 } elseif ($Choice -eq "5") { Write-Host "Please stand by, this can take a while depending on the number of updates." Write-Host "Slipstreaming updates to Windows Server 2012 R2..." $WimFile = $WimFile5 $UpdatesPath = $UpdatesPath2 } elseif ($Choice -eq "0") { Write-Host "Exiting..." break } #Mount the image in the temporyar mount path specified above. &$DISMPath /Mount-Wim /WimFile:$WimFile /index:1 /Mountdir:$MountPath #Apply the patches and show progress. &$DISMPath /image:$MountPath /Add-Package /Packagepath:$UpdatesPath Write-Host "Updates Applied to WIM, scroll up to check for any errors encountered." #Commit changes to image that is currently mounted in the temporary mount path and write to disk. &$DISMPath /Unmount-Wim /Mountdir:$MountPath /commit #Clean up any mounted images. &$DISMPath /Cleanup-Wim } #Return to the menu and wait on user input. while ($Choice -ne "0")