I installed the air pressure switch today and it is working perfectly. It threaded right into the T fitting that was on the truck.
I had to make these wires to add some length to what was already there since this switch is quite a bit lower than where the original is supposed to be.
Here it is installed. I am going to test it a while before I make it more permanent. You can see the original switch in the background. It will be taken out soon. All of this is under the dash and not visible while sitting in the seats.
I also took the buzzer that failed apart. Here are the internals.
The problem is that the ground wire over on the right hand side burnt up somehow. It looks like an easy fix, so I am going to repair, reassemble and test for function when I get a chance.
A month or so ago I mentioned that a friend of mine built me a good muffler out of the two that I had. I also mentioned that the Army Veteran friend of mine that used to drive these trucks in the service in the 50's said that they used to remove the internals of the muffler immediately upon getting a new G749. I have had some time to test the truck with the "new" muffler on and I have to say, I do not like the way the truck runs with it. It is not as powerful as before.
My next plan is to weld an end on the hollow muffler that was left from my friend rebuilding the one and to install it to see if the truck runs better that way. The Army Veteran friend of mine said that the truck would not be noticeably louder with the muffler internals gone but would run better.