In 2wd the locker shouldn't be doing anything, so long as it is operating correctly!! Had a local XJ owner with similar issue.. he thought it was a steering issue or something else, so he replaced the steering gearbox (upgraded to Durango box)... and it helped some, but was still having the same issue, except for his seemed to be locking up in either turn direction... Told him to me it seemed like a locker issue, which he was told by the PO that it had no locker... after he tore the diff cover off, he found out that he had what is called a Volvo locker (apparently out of a few different model Volvo's that have a 8.25 differential).. come to find out it was busted, and so it we locking up whenever it wanted.. so I would think with that one having an auto locker, I'd say pull the diff cover off it, take a look at it and see if you might be able to see any kind of writing or symbol that might help identify what kind it is, to see if there is anything that might look out of place right away... Almost wondering if the springs inside of it, might not be missing or just worn out... fairly easy to get the parts and swap them out..