When the army rebuilt the Garands in the 50's and later did they ever add the last two numbers of the year to the number?

for example on my Garand the trigger housing has the correct number, 28290-sa but the numbers 55 were added to the front so it reads, 5528290-SA.

The hammer for my period rifle according to duff should be c46008-2 SA. On mine you can see were the "c" was taken off and the numbers D55 added so it now reads D5546008.

on the bolt it should read D28287-SA but you can see where they over stamped the "D" and it now reads 6528287-SA.

Any answers on this?

Nope.  55 and 65 series numbers are the postwar drawing numbers.  They changed a lot of the drawing numbers after the war and that's what they denote.   You'll find them on trigger housings, hammers, bolts, oprods, barrels and receivers.  

They did'nt overstamp the bolt, or trigger housing, The "65" prefix was used after the war..All 65 prefix numbered parts are postwar parts. In the case of a rebuilt rifle probably new replacement parts,  I seriously doubt the Army depots at the time would waste time restamping used parts. When these rifles were rebuilt parts were replaced with either new, or used in spec parts, no effort was made to keep orginial parts in any rifle. Parts used on any rifle were the ones taken randomly from the bin, so you could get new, used or both,