I tried to install the SP1.c for the 737 NGX 600-700 and I get the "The setup has detected no version of PMDG 737 6700 NGX RTM is installed." I was able to update the 800-900 but not the 600-700.

Firstly:

 

Uninstall the 800/900 NGX to reinstall. Once the installation is finished, you download and install the SP1C for 800/900NGX.

 

Secondly:

 

Installs the 600/700 NGX. And download the SP1C 600/700 NGX.

 

Let me know.

I took a closer look and my problem was I never purchased the 600-700 that is why it could not find it.

If you installed the SP1C without buying the 600/700, I can understand the reason for your problem.