T case troubles.......

I have a 99 xj 4.0 manual with an np231 and an SYE sitting on 6' and 31-33" tires. here is how it started
A few weeks ago i was pulling a trailer slow through the woods never pushing it. i would hear a pop if i was turning and asking for any kind of power i 4wheel but it wasn't consistent.
since then i was trying to get on the beach and could not give the car any gas without a bad popping and now 4 wheel drive so it seemed
2wd works fine. 4h and 4l will pop like crazy and not go anywhere but i never pushed it too bad
so it seems to be the chain and my question is what should i expect when i open this thing. new chain? new t-case and or SYE? iny input would be really appreciated thanks

Probably just the chain gone. Whenever you open one of those things it's a good idea to anticipate bearings, seals, and shifter pads.

are you sure the shift linkage is adjusted correctly? the first part sounds like a loose/stretched chain, but the second part sounds like it's not engaging completely.
a loose chain is an easy replacement if you have basic skills. if it's that loose i'd inspect the housing, because a very loose chain can ride against the outer housing and wear down the aluminum as the chain spins.

i have played with the linkage and think it is the chain instead of the linkage i guess i wont know untill i open it but was hoping justa new chain would be the bear minimal. any good places for a rebuild that includes a chain? also really hoping the SYE is fine.

I'd just get a new chain, timken rebuild kit, and new shift pads. Shouldn't take you more than a day to do.

and a real good set of snap ring pliers...