Maybe some other people have had different experiences with there 242, I've never had one jump a chain. I've had other model (full time) transfers stretch and jump the chain. It usually first shows up when trying to power against something immovable, like a rut or a rock, then later it may jump when you throttle hard.
If your not in 4 full or part time, there should be no drive to the transfer chain. It just kind of free wheels, it may rattle some, but jumping in 2 WD IMO seems unlikely.
I've had really worn front U-joints pop pretty good when in 4X and put under strain.
I'd look at my rear drive shaft U-joints first if it's acting up in 2 WD. Then the exhaust where it passes over the cross member. Possible it could be something in the rear end, a chipped tooth on the spider gears or something, I had one set of spider gears loose a tooth. I was thankful the chipped tooth pieces never found it's way into the pinion and ring gear.
Just for a reference the 242 in my 88 is just about worn out, the front shaft has a bunch of play (bearings) and it's doubtful I have any shift fork pads left, chain has never jumped.