These black painted numbers on PX swords are called subassembly numbers. They were merely to keep the parts together when the sword was being assembled at the factory. They would simply restart at 1 after reaching 99 or 100.
The exception to this subassembly method is the PX swords made by Mitsunaga 光永. I have yet so find one with black painted numbers.
Conway, your getting good at this! Below is the full inscription excluding the polisher which is lost to pixelization. As Bruce indicated, the swordsmith is Ishihara Masanao.
謹作高山刀 刀匠 石原正直
PX sword with a subassembly number of 四六. I am starting to think these grow on trees. They are everywhere. Maybe Mr. Stroud is mass producing them in his basement to sale to unsuspecting tourists in Puerto Rico!
Suggestions on replacement of the Kashira or end cap
Douglas, I note that your sword has two subassembly numbers on it. One on each side of the tang. My question is which of the two numbers do the parts match to, 7 or 64?
There is actually a difference between a plain anchor as seen above and the one used by Tenshozan. Note the additional details in the Tenshozan anchor.
TENZOSHAN FORGE.jpg
It seems the Type 97 seen in images 5337, 5339, and 5340, has a plain anchor mark. What I mean by this is that the anchor does not appear to be encircled. This is only the third sword I have seen with this type of anchor.
Shigemitsu & Nakago Stamp
The Naval Type 97 Military Sword was made in about 1942 or 1943 by Tenshōzan.
天照山鍛錬場作 = Tenshōzan Tanrenjō saku.
Search Terms
Type 97, Tenshozan, Kaigunto.
I found all these by doing a NMB search using the term Anchor. It yielded 15 pages, I then sorted them in chronological order, and started with the oldest posts first.