Here is another image showing the IBM markings. The dot next to the I makes it look like the letter L.
Most of the markings are hard to read.
Here is one new in the original wrap.
The one on eBay was probably marked back in the 1990's. Back then unmarked slings were hard to sell, but those with markings sold very fast. There are not only fake markings on legit slings, but there are also fantasy marks which never existed.