I looked at the overall situation and decided that it would cheaper and better to swap in a manual shift BW4406 from a 1997~2003 4.2/4.6 F150. This transfer case bolts directly to the Explorer's 4R70W and the T/C linkage even bolts up to the 4R's extension housing.
Because of the size difference of this case, you'd need custom driveshaft lengths front and rear. For my 2003, the front driveshaft from the same 97~03 F150 fits with a 1310/1330 adapter u-joint. Not sure what you'd need for the front shaft of the 91 but any driveshaft shop can fix you up.
I paid under $400 total for the transfer case, front shaft and rear shaft mods. Add another hundred for the linkage and assorted parts and you're still well under what the AA 1350/1354 adapter kit and oil mod kit would have cost. On top of that, there's no need to pay to have the automatic disassembled for the kits. As a bonus, the larger transfer case is designed and intended for use behind a V8.
Downside to using the larger 4406 case? Size. The clearance to the left frame rail and the fuel tank is very close in my 03 and could need some clearancing for other years. Don't know. If you don't have the extra wheelbase of a supercab, take a lot of measurements of the truck and case before buying. The 4406 case has a large tailhousing on it, making it not only wider than the 1354 but also much longer, front to rear.