I finished removing the auto front axle engagement valve and the shift lock solenoid from the T-case. Neither are used anymore and both were leaking. It was pretty straight forward with the use of a couple of fittings. I did find that the shift lock solenoid had never worked because both wires were connected to ground. Will have to pull out the wiring diagrams and check the remainder of the wires in that area.
The only air going to the transfer case now is from the dash switch. The only thing the T-case shift lever button operates now is the 5th gear lock-up solenoid.
Although it was easy, it was far from clean. All these parts and fittings are directly in line with the jack shaft u-joints and were covered with years of grease. It looked like I had been repacking wheel bearings instead of swapping air lines.
I let the truck sit for 18 hours after I was done and only lost 10 psi. That was well worth the effort. Then...I check it again about an hour later and was down to 90 psi but holding sready. WTF!
I cut the shop air back in to find the leak and could hear it in the cab. Turns out I blew a wiper hose right at the driver side dash valve. At least that happened in the driveway instead of on the road. I cut a fresh end for now but looks like wiper hose replacement is next.