Those arbors were close to $150 each back in the late 1960s.
The standard arbor is a 1" short arbor for single blades. For dado blades there are long arbors, but they can interfere when tilting the blade.
Delta offered arbors in 1", 1 1/8, and 1 1/4" short and long.
Grizzly made a copy of the Delta 12/14 saw, the Grizzly G5959, they had arbors for sale, but I heard they have run out. They made a 5/8" arbor that Delta never did.
I went ahead and made a 1" dado arbor, and a 5/8" arbor to use blades I already had, rather then buy from Grizzly.
When installing the arbor, it does not need to be much more then finger tight, the nature of the mount requires the tapers to actually have to rotate before the fine thread can actually push the arbor out. If too tight, that can be very hard to do.
In use, the arbor assembly heats up a little, if an arbor is removed hot, and replaced with a cold one, it can get severely stuck.
Easy project to make,