Be very careful when you get the old tumbler out to carefully inspect the opening in the steering lock assembly still in the car. When I did this at a DIY Tech Session at ASC in Alexandria, the techs didn't think it was a big deal and told me go ahead don't worry. There is a tang on the tumbler that inserts into the steering column lock assembly and on mine, it had broken off. If you don't notice this tang and put the new tumbler into the opening, the old tang is jammed in deeper by the new tang and you will be lucky to get your steeering column assembly out without drilling.
I was lucky enough to have Marvin, one of ASCs team leaders, generously offer to help. For the next two hours he torre my dash out and worked to get the steering column lock assembly out without drilling into the side of the column. He was able to, but I would have likely towed the car to a dealer if I had done this at home in my garage.
Not trying to scare you off, just giving you a tip from one who has seen this job go south quickly.