I got around to installing the Truck System Technologies tire monitoring system yesterday and all is well. Both the truck and 5th wheel tires are up and reading. I used the pass through sensor all the way around. I left the stock pass through extensions in place to give room for the sensors to turn when installing them and on the outside dual I need one more flow through cap because it points inside and a cap would not work without removing the wheel again. I did remove the outside dual to mount the sensors on the duals. The outside wheels are also rotated 180* so the stims are opposite each other so they line up with the holes correctly. I originally thought I would use the flexible valve extensions but my tire dealer said they get them in often with people thinking they have a leaking tire but it turns out all too often that it is the extension leaking.
Time will tell but so far so good with TST 507 system. Now the search is on for a good place to mount the monitor. On my F350 I had it mounted on my dash but the backlight is not auto dimming and it was rather bright when maneuvering in tight spaces at night. I had a piece of cloth to put over it and may end up doing the same thing this time. For now, I am just glad it is working.

 

I guess that's what you gotta do if you want to see air pressures in an F-450. Well, at least you have that info available to you now. Good luck with it.