I wrestled with a RWD Caddy telescoping columns for one of my project vehicles. Too Many To Count identified the missing locking bolt and plate but there are a number of hidden glitches that lurk below the surface of the Caddy column.
If you were lucky enough to get a key with your column you have half the battle won. Without it you need to us some strong-arm tactics to get past the colum/transmission lock feature. Shortening the column 2 " was challenging and after I hooked it up to the C6 transmission I discovered that there was a detent feature built into the column that didn't match up with the detent system in the transmission. Ultimately, I wound up having to go with a Lokar Floor shifter as the two detents fought with each other and catastrophic transmission destruction was lurking during hard acceleration.
You're fortunate to have a wheel you like that fits the GM splines.....a Grant adaptor for the Caddy column was $85.00 at the time, so I wound up fabricating my own to match the brand of wheel I wanted to use.
When it was all said and done, I would have been dollars and cents/labor ahead to have sprung for an Ididit/Flaming River tilt column as I had to lock out the telescoping feature. I guess it was a case of "Live and Learn." Hope you don't have as much of a problem getting your Caddy column adapted to your truck.
Dave