I installed factory cruise on my '69 Charger. There were 2 dimples on the inner fender indicating where the factory bracket would have been located/bolted. After drilling out the dimples for the bolts, the bracket fit great. Check your inner fenders to see if there are dimples there.
If there are no dimples, this may help. The mounting bracket is the same for 68-70 B bodies (even though the cruise unit itself changed in '70), so any of those cars/pics you can find will be a help.
Feel free to pm or email me if you have any questions about my install (email is in my profile).
I go to several car shows each summer that are 1-3 hours one way, so the cruise is great to have.
If I could not have found enough parts and/or not gotten the factory setup to work, I was going to look at an aftermarket install.
As already mentioned, '68 & '69 are the same cruise systems.
Don't have any pics of my car but here are 2 I found and saved for reference before doing mine.