This is an opinion, really. Anyone can do what they want with the black regulator on the inside of the frame rail. They are there to adjust the amount of air required to operate the air-o-matic system according to the conditions that prevail in a particular area of operation. If the owner understands how to adjust it without breaking it, I believe it is worth keeping on the truck. Because......... The upper regulator on the firewall is not adjustable, it is on or off, and automaticly stops air from going to the draglink in the event of the truck air system falling below 60 PSI. This is to help save remaining air reserve for braking, etc.
Now, my other opinion, this time from experience with these kits and many Deuces with Big tires and little tires, and M35s, M35A2s, and 2 M35A3s: The steering gear box is the weakest link in the entire system when it is abused by having the truck sitting still and turning the steering wheel. It is showing up in M35A3s with the wider front tires. The Ross steering gear vbox is more than adequet for 9.00x20 tires and the original Reo OA-331 Gas engine, as it is a lot lighter than the Multifuel.
As far as the Air-o-matic weak link, I haven't found one in 14 years of running them on my off road dump truck. I grease the zerks and have adjusted the draglink cups once, Rubbed an airline almost to the point of leaking and had to replace it. That is the Maintanence I have had to do on a hard working truck with air-o-matic assist.
Thanks, JT out