If the knife was made/carried/used/all-of-the-above prior to 1961 or 62 then...for sure the sheath is much newer than the knife. It is a Model #3 sheath and the knife would be better fitted in a Model #5 shaped sheath. More than likely, the sheath and re-handle were done later on in this knife's history and the sheath was probably chosen because the knife fit in it OK...if not correctly. Hope this helps.
Best, Capt. Chris