ALL carbines in service at the end of WWII were Arsenal inspected, and updated to use the bayonet equipped front-band. Any that had worn parts were also updated with the latest parts available, and many were re-parkerized. The added parts were from whichever manufacturer they had on hand. The weapons were dis-assembled in batches, and the parts were checked, replaced, or refinished, and THEN the guns reassembled from bins of inspected parts. THAT'S where the "mix-master" (an old-time electric mixer brand) reference comes from. AFTER the initial re-work, carbines were placed in storage, re-issued, or sent out in Military Assistance packages. Germany, Korea, France, Holland, Japan, and Thailand all received them. As did the Vietnamese. Many of the late-80's early 90's carbines imported commercially were from Korea.
After Korea, this was done again, and some were even re-arsenal built after use in Vietnam.