OEM's include the bracket for the plug, but most after market do not, as they
do not know where you want it, need it...nor what kind of plug you want to
install
Here is a link to how I added a plug bracket (they come with the plug and if
you already have the plug, you can purchase just the bracket) to my OEM receiver
That era, GMT400, GM full sized still had a traditional design receiver so it
should be very similar to yours
1996 Suburban tow harnessand this is the image of how it came out and during the install (drilling)
Vice Gripped to hold while drilling into the receiver
Done