Sorry, my previous post left out some important info.
If your steering wheel is 180 out then somebody had to replace the rag joint. With the factory rag joint the end of the steering shaft has "ears" on it that are captured by the portion of the rag joint and then then riveted in. To replace the rag joint the lower shaft has to come out, grind off the rivets and the new aftermarket rag joint uses bolts instead of rivets.
If the plastic shroud is not covering the rag joint (the shroud is there to keep grime and grease off the "rag" part of the rag joint and prevent premature rotting) you should be able to see the bolts. Most likely you will have to remove the rag joint from the input shaft of the steering gear, pull the lower steering shaft with the rag joint still on it, take to the bench and unbolt the rag joint from the shaft and rotate it.
Here's link to the only aftermarket rag joint available for these trucks to my knowledge. Pic #2 is the shaft side.
If you have the plastic shroud off, you will be able to see the difference between the factory style and aftermarket style rag joints. (Note: The plastic shroud on my 96 and 97 K1500's are impossible to slide up the shaft without loosening the steering gear from the frame to provide a bit of clearance from the crossmember.)
I've replaced my steering gears because they begin to wear out at about the 140k mark in my experience, and the aftermarket parts stores rebuilds are a POS that either come with 3-5 degrees of play out of the box or will have that much play by the 10k mark.
Having said that, my spare gear is an Oreillys (two Oreillys, one Auto Zone, and a BBB Vison so far) with 10k on it, and has, maybe, 2 degrees of play. Miracles do occur. BUT, the steering gear I replaced with is a brand new manufacture BBB Vision that cost me $450. It came out of the box with, you guessed it, around 4 degrees of play...