I doubt if the local electrical supplier would carry them, you might get an equivalent in Ferraz Shawmut or Gould Shawmut, but they most likely would have to be ordered in.
They appear to be rectifier fuses, if so they would most definitely require ordering in, and expensive, on average $100 ~ $250.00 each.
If on the off chance these are not rectifier fuses, it may be expedient and less expensive to fit in a current style fuse block with suitable fuses.
I don't know why you would have rectifier fuses on a buffer, unless you have a solid state drive of some kind.
Looking at the Littelfuse link, they just appear to be ordinary fast acting,
Rather than fast sweep through Rectifier type.
Al. .
CNC, Mechatronics Integration and Custom Machine Design
“Logic will get you from A to B. Imagination will take you everywhere.”
Albert E.