Almost got my 249 dropped and the other one in when i encountered this problem.
231 Shift Indicator Sensor
The NP249 sensor WILL NOT work in the 231, as the threaded portion is about 3 times longer. I attempted to shim it to no avail. XJ cases do not have the proper provision to have a fully functional VIC, however you can use the 4wd switch on the XJ to show "part time" when in 4wd.
Should i use the plug from the xj harness and just solder it onto my wiring harness? Does anyone have a picture of this shift tab? I have to go back tomorrow to take my core back and i want to make sure i grab the right thing.
It took me 3 hours to pull the one in the JY. It had a factory Transfer Case skid and all 3 bolts holding it to the unibody and the cross member were free spinning. My transfer case removal, and installation of the 231 took me all of 1-1.5 hours. It was pretty quick. I still am lacking the transmission mount, cross member and both drive shafts. Which i estimate to take another .5-1 hour depending on how hard the transmission mount fights me going back in this time.