Update. I replaced the complete MC on Saturday, everything is good now. I was an easy process,
I had my daughter help with the brake bleeding process. The whole job took maybe an hour or so to do.

GM only sells the complete MC including the two Proportioning valves. The list price is $192.00 but I have a
buddy that works at a GM dealership and he got it to me for $120.00

Before I purchased the new MC I tried to tighten things up but that was a no go. Everything was very tight.