I didn't quite have as much issues as Eric above to fit it in place, but close. I had different issues that were time consuming. Like Eric, the L&R plate was very close to fitting the existing inlet, but the bolt was off by probably 3/8". It was close enough the escutcheon on the other side still covered the prior hole, so I never bothered to fill it, there's just an oblong hole there now. I did have to inlet deeper to make room for the springs, and like Eric's picture above I had to shim the rear of the inlet. I used a block plane to shave end grain from a scrap of walnut, 3 shavings stacked filled it in. so i wood glued them in place and shoved the lock plate in to compress it. Once dry, I scraped it and dabbed a bit of tru oil on. My touch hole was luckily aligned with the pan, so I didn't have to fiddle with moving the barrel thankfully. All in all it took maybe 2 hours. The bigger problem I ran into was something was off with the miling of the tumbler, knowing what I know now, I should have sent it back and asked for a replacement. Being a DIY master in my own mind, I started filing and stoning which lead to filing and stoning just about everything. Probably 30 hours later I finally had a well functioning lock (if it's not right, send it back, I hear their support is very good).