Muy amable. De nada

It would have been possible to have everything run at 100psi....but I guess the lower pressure allows things to still operate in the event of an air leak

@@OldCrowsClassicCars Possible, but what are the chances that a piston large enough to operate at 70psi slams the parts around hard enough to damage them at 120psi. Then if you design for it to not cause trouble at 120psi it doesn't move reliably at 70psi. The reality is that the air force available can vary wildly. 120psi is 172% more force than 70psi, and 70psi is only 58% of 120psi. Air leak? dude if you operate the brakes on these vehicles the air gets used, so you can drop the air pressure by pumping the brakes. Many have great compressors and don't drop much air, but others really see the pressure drop when you pump the brakes a bit too much.

When you say last 2 gears is it the OD gear?

Did you get that figured out? I’m having a similar issue with my 13 speed. When I shift from a high split and upshift to a low it grinds and rpm drops too much

If you fuller doing good air pressure you don't do neutral then gear on

I'd say not in your case because a faulty regulator would cause problems in a whole Range not engaging...so basically no HI range gears for example. The OD solenoid controls the OD or finla gear so from what you say, that might be your issue

Gracias por su enseñanza le saludo desde North Dakota soy de el Salvador