I have not worked on or operated a 79 column.
What I can say for sure, the pot metal bracket that is in the column you are working on is exactly the same as the pot metal bracket on the replacement switch.
The picture below is of a Late 1979-1982 (Left) and the replacement switch on (Right).
I put a RED X on the paw that pushes on the actuator you are missing, they are exactly the same size shape and placement.
That columns dimmer rod should work just fine, once you find the actuator...

 

Cool, thanks again for your help. Found a actuator on fleebay. Forwarded that information to the owner.
the actual wiring should be a chip shot. Thanks much to your previous thread on this new switch installation and all your help in this thread.
THANKS Joe!

 

I want to make a correction, not that will change anything for you.
The photo on the left I posted above in post #21 is of a 1978 2nd design - Early 1979, not a Late 79-82. I just mixed up a couple photos...
Here is the progression of that setup, the 1977 uses the pivot bolt as well as the 1978 1st design.
After that GM went with the solid pin for the pot metal bracket...
Notice, all the brackets are the same in size and shape as well as the paw that contacts the dimmer actuator, the item your missing.
Basically, only difference between the 1978 2nd design - Early 1979 and the Late 1979-1982 is the turn lever and it's angle...

 

Stumbled onto this thread researching various issues I've experienced replacing the lock cylinder in my 77. I must say, bmotojoe, you seem as comfortable with these columns as the legend Jim Shea, whose documents and pictures I used extensively to help me. I'm hoping you might be able to help me answer a few questions before I reassemble and further exacerbate a potential problem I caused by straying from Jim's instructions a bit.

What prevents the lock wedge from coming out with the upper steering shaft? I'm guessing it is the C-Clip. For context, in Jim's 15OC2013 Paper #1 under the "Telescope Lever Adjust" Jim states, "You can now remove the “star” screw and check to insure that the lock rod #40 is in place. You may need a small magnet to pull it out of the upper steering shaft #41. You will not be able to remove the lock wedge #43 at this time." [emphasis added] That was true on mine right up until I removed the C-Clip, now the wedge and upper shaft come out easily.

To make a long story longer (and further advise why I am concerned), I also watched a YouTube on how to replace the locking cylinder. The video correctly cautioned that a common auto parts compressor tool wont work on a T&T without installing a 5/16" coarse (18) x 3/4 inch socket cap bolt in where the star screw goes. The socket cap bolt would engage the rod, pushing the wedge and locking the telescope. Jim's paper refers to this as: "In order for the bridge tool to work, the upper steering shaft must be prevented from telescoping. You must place the shaft in its shortest position and lock it in place by reinstalling the locking rod #40 and then tightening the “star” screw. Also note that some of the special bridge tools may interfere with the “star” screw. If this is the case with your tool, you will need to install and tighten a 5/16-18 UNC set screw (#20 Allen screw) in place of the “star” screw." My problem was that the 3/4" length socket bolt was a tad short to engage the rod/wedge. Next size up, a 1" length, was too long and prevented my compressor tool from threading onto the shaft.

Not to be so easily dissuaded, I pulled a farmer fix and cut two wood blocks to make up the distance of the telescope shaft at full extension (it wouldn't come out) and compressed away. Perhaps the difficulty releasing the C-Clip should have been my first sign that my fix may not work. Suffice to say when the C-Clip did come off, the upper steering shaft/wedge shot out into the seat (likely lucky spring wasn't more compressed, but I always have a bad feeling about springs under compression so my face was way out of the line of fire). Here's a pic of my revised tool:



Now I have a new problem - if it is in fact the C-Clip that holds the wedge back, my revised tool won't work and I'll have to go with a different plan - building my own tool using a 5/16-18 x 6" or 8" bolt/carriage bolt etc.:



I can then thread the compressor into the inner shaft until the wedge sets on the telescope, tighten using the bottom nut, then tighten the top nut and viola. (Note the picture is a mockup using carriage bolts I had laying around - not the right size bolt.) I think this will work if it was indeed the C-Clip preventing the wedge from releasing.