That’s the thing, the front axle currently in mine doesn’t have a vacuum actuator on the axle. It’s just a plain old solid axle. The dash 2hi/4hi selector is there and a little bit of some vacuum lines with it and that’s it.Read about the 228 here. The Novak Guide to the New Process 208, 219, 228 & 229 Transfer Cases as found in FSJ & XJ Jeeps, 1980-1991
"The NP228 had a direct-drive 2wd mode. It used an internal, open differential for four-wheel-drive mode and high range and featured a fully locked mode in four-wheel-drive, low range. It featured vacuum actuation for mode operation and a conventional shifter linkage for range operation. This transfer case was used in the XJ Cherokees as the optional in lieu of the NP207.
The NP229 was similar to the NP228, but it featured an internal viscous coupling for full-time operation. This transfer case was offered in the FSJ Grand Wagoneer."