Maybe Timney changed the design at some time. I installed one on my Bubba'd NM 5-6 years ago before I restored it. It involved removing quite a bit of wood in the trigger well so the assy will fit without binding and the timney trigger is wider than the OEM trigger so the slot in the guard has to be widened and lenghtened. Depending on the trigger bow depth it may also be necessary to shorten the trigger itself. It's definitely not a drop in fit in a military stock. I also have a Dayton Traister Mk.II adjustable trigger for the 1903/a3 thats very close to the profile of the OEM trigger/sear assy that does'nt look like it would involve much if any mods to fit, minimal wood removal at most. I just could'nt bring myself to do even this little bit to a pre-war Springfield C stock though. I'll part with either or both if you're interested.