Hello everyone, i'm new to this forum but not to the whole automotive forums as i'm a member in multiple forums. I have some questions regarding a truck that was passed down to me from my uncle.

Year:1996
Make: Chevrolet
Model: K/2500
Engine: Vortec 350
Transmission: AT 4L80E Floor Shift 4x4
Mileage: 245000

My question is regarding my transfer case. All gears in the transfer case can be shifted into and shifted out of. And all gears do work. 2hi, 4hi, Neutral, and 4lo work. However, when gear selector is in 2hi, sometimes(it has happen twice) when hitting a bigger bump going down the road, it would shift itself into neutral. When this happens, I just pull over, stop, put transmission into neutral and turn off the car, and then just simply shift the transfer case back into 2hi.
When shifting the transfer case from 2hi into 4hi, i feel detent locking the transfer case into 4hi. When shifting from neutral to 4lo, i feel detent locking the case into 4lo. When i shift from 4hi to 2hi, i only feel a very very slight detent locking it into 2hi. Also when i shift from 2hi to neutral, i don't feel any detents. It feels like there's no detents preventing the transfer case to not shift into neutral from 2hi.
I took a look underneath and the linkage seems find. This being my first gm truck, i don't know if it's a common problem or maybe just the mileage on the truck taking its toll on the transfer case.
If i'm mistaking about the transfer case having detents to hold the transfer case into gear, are they held down by return springs within the transfer case? Can anyone with more info and knowledge confirm this?

Sorry for the lengthy intro and problem. Thanks for any help and replies.

Edited** IDK why i put 1994 in the title but the truck is a 1996**

 

So right after posting this thread, i drive the truck to pick up my brother. Filled her up with a full tank of Holiday 87 on the way and 46 miles after fill up, she blew a hole through the driver side block!!! At this point, i don't know what could have cause this. Traffic was cruising at posted speed at 70 and i set my cruise at 65. I hear a big POP and she started smoking everywhere. I pulled over, pop the hood and there was oil all over the driver side of the engine block. I pulled the wheel apron up front to see the damage and there she was. A hole on the side of the block about 4" wide. Towed her to my work place and will start tearing her up tomorrow. I will try to post up some pictures today of the damage.

 

As promise, here are some carnage pictures:

 

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