I was hesitant about the dual needle gauges myself but in the end I decided to give it a try and see how it worked. I spent around $30 for the Viair gauge, (I think the ISSPRO air pressure gauge is around $160...)

I pretty much had to cobble something together quickly since I was short on time and didn't really know what I wanted exactly. So, I ordered a blank F650 manual trans dash, the dual needle gauge and a variety of switches. I then would figure it out when all the parts arrived. My F250 has the F-650 dash for automatic trans and that works great since I have the center console....but my F-450 has the center jump seat so I went with the manual trans dash just so a middle passenger could have some reasonable leg room when riding in that spot.

I am not quite done yet...I need to mount my CB in the bag holder spot, install my engraved label plates and maybe repaint the dash the correct color (undecided on that last part..) The air pressure gauges work OK the way they are. The gauge on the left came from an Airlift compressor kit...I just removed the components from their mounting bracket and re-installed into the F-650 dash. Black momentary switch controls electric air valve solenoid to air up the fifth wheel hitch. The push valve below lets air out of the hitch.

The Viair gauge on the right replaces the Firestone gauge I had originally and provides a second needle for air tank pressure (Air tank in red and rear suspension bags in yellow). The red UP button on the right is wired to a solenoid valve on the air tank. The black DOWN button just below that is the dump valve, which causes the truck to 'kneel' when unhooking the fifth wheel. The switch on the far right is air compressor that is wired to a pressure switch in the tank (cuts power at 140 psi...)

Now that I've towed a few times with this truck, I can report that the gauges work fine and are quite legible during the daytime. However, Illumination quality at night is far inferior to ISSPRO gauges. If I was doing a lot of towing at night, and had $480 to spend, then I would definitely prefer ISSPRO gauges. I am not sure why the ISSPRO gauges are so expensive...they might be 100% electric and have a remote pressure sensor. If so, that would be pretty cool and somewhat easier to install. Keep in mind that if you plan to have dump valve controls, then you will be running air lines inside the cab anyway. Just food for thought...

Here are a few pics....not the cleanest arrangement, but it works OK. I think I have about $120 into this (including the F-650 dash)

 

I'm running the Airlift system with on board air on my Excursion, it has a digital controller with individual readouts for each of the bags (left and right). I fill each to the desired level and leave it, it replenishes if needed to that pressure. It is a more work and stuff to install; plus you have to indivdiually set the pressure to each bag, that is not an issue for my needs.
I do have the external fill valves in the license plate frame as well, just in case the on board air quits.

 

Nice set up greg. But like I said, I want the ISSPRO gauges. Why? Because they match factory, and my other gauges. It is worth it to do this project once, and do it 'right' (by my rules) the first time. I want them to match. I could also go to radio shack and buy $2 toggle switches, but I dont want my set up to look cheap, so I am going with quality switches that look nice.

 

Nothing wrong with that. Half the fun is doing things our own way.
The Autometer factory match gauges are a better match...almost exact. The font, increments and illumination is spot on. Even the dimming feature works perfectly. Problem is that Autometer has a very limited selection of gauges in their Factory Match series. I never could understand why they did that.

By contrast, ISSPRO has almost everything you could want. Heck, they probably have too many choices (if that is even possible...) I can't wait to see how your set up turns out.

 

Yes they have many gauges. I even spoke with them and they said if I did do an independent system they could make me a dual needle PSI gauge.. SPECIAL ORDER

Cant wait, my set up should be great, but it may be a while out.. depending on...

I've already said too much