If I understand Bob Best correctly, the fact that it retained its entire butt serial when it was upgraded from Model 1896 to Model 1901, with the swivel, means that this happened at Colt, not at an arsenal, where the Army often just restamped the last four digits taken from another part. Thus the occasional supposed "first-year" guns floating around Gunbroker and such.This much reworked Colt has the deeply-struck main serial “No 150354” on the butt, right below the “U. S. Army Model 1901” and the lanyard ring. On the left side of frame is “R.A.C.” with the cylinder latch marked “K / 354”. Again, on the frame inside the crane, is “R E / 354”. On the crane, just forward of the cylinder is “K / 354”. The rear of the cylinder indicates that some rework has occurred with “R.A.C. / 3204 / P / C”. Just ahead of the frame, on the underside of the barrel, is “RAC”.
Considering how much reworked this Colt is, it's ironic that it escaped the most prevalent rework, the Remington contract from 1918, recognizable by the L.E.B. stamp. That covered pretty much the entire Army inventory of these still on hand when they were mothballed after 1909.
Mine shipped originally in October 1901 to Benicia.