I had to remove a little material off the grip safety so it would lift over the trigger bow but otherwise it was drop-in and very simple. The hammer dropped right in except for having to transfer the hammer strut. Trigger feels good. The factory thumb safety dragged a bit after the hammer install and I'm sure it has to do with the new hammer engaging the sear at a different angle or some-such. I had a thought and for grins tried a Wilson thumb safety Ol' Dan gave me years ago. Boom! Popped right in and engages perfectly and snicks on and off positively and slicker than snot on a doorknob. Very happy with it. Now to test fire it when I can get back to the range.