Akulahawk - That's a real nice Garand. Rifles in that serial range would normally have barrels dated Apr & May 1956. It is believed those rifles were assembled between mid summer 56 and early spring 1957. Your barrel, dated 10 of 54, is interesting in that the 1954 barrel is a common trait of type 2 NM rifles. A cache of 33,000 barrels, dated 1954, were uncovered and grabbed by the NM program in late 1959. As between 1960 and 1963 less than 15000 NM rifles were assembled, that would leave another 18000 of these barrels that could be used on service rifles, as replacements during a rebuild. I see what looks like N and a M on your barrel. I now read in another by Bob Seijas in the Winter 2003 GCA Journal that the letters NM were stamped on the barrel. Also check more toward the chamber area for ""P T". Your barrel shows only one proof. From what I read in an article by Bob Seijas, in the Summer 07 issue of the GCA Journal, the barrels that were installed on the NM rifles had two proof firing P's, one having a prick punch inside the loop in the "P" and another P without the punch mark. First "P" when barrel is tested alone, the prick punch when assembled and proof fired, and the second "P" when proof fired as a National Match. I am not sure this was the case with the 1954 barrels. Also NM was stamped on the top of the barrel between front sight and front handguard.
When the assembly of NM Garands ceased in 1963 there were still alot of NM parts and these were used in regular service rifles during rebuilds. What bothers me is the fact that most rebuilds from the mid 60s, that were done at major depots and arsenals, were marked on the right receiver leg, by electric pencil, with the initials of the overhaul facility and date of overhaul. Overhauls that took place at other than major facilities or overseas facilities were not documented, so this is a possibility. I would hope to hear more on this rifle from someone with more knowledge than me. My guess, and it's nothing more than a guess, is that your rifle went through an overhaul in the mid 1960's. On the other hand you might want to check this rifle out more closley. Seijas also states that over 5000 Type 2 NM rifles went to Greece in 1974. The Greeks replaced the match sights and used them as regular infantry rifles. When they were obtained by the CMP the condition was the same as the Greek Service Grade. Maybe, somehow you lucked out and got one of these.