there are 4 bolts that hold the aluminum tilt "base" to the main column body tube. these 4 bolts work their way loose after many miles & many tilts.
they are an easy fix but there is a lot of disassembly to get to them. if you have never had a GM column apart before, take pictures as you take it apart - there are a LOT of little pieces & if they are not back together in the right order the column will not work right. I have fixed several of these & it will take a couple of hours to take it apart & put it back together again if you have not done it before.
while it can be done with out special tools it is easier if you have a puller to remove the wheel (a harmonic balancer puller works good) and a lock plate removal tool. the lock plate is tough to get off without the right tool. most automotive supply stores should have one is stock, the lock plate has been the same in GM columns for 30 years + (since about 69). i bought mine for about $20. it also helps to have the puller for the tilt pivot pins (about another $10).
when you have it apart Loctite the 4 bolts so they will not come loose again. If you get good at it you can make a little money fixing the loose ones in your area. the same column design is in all GM vehicles up to the late 80's/early 90's.
If you get it apart & need any advice or have any questions just ask, i will help as much as possible.