It won't have the detent ball, but just buy a 3/4" hex wrench or a piece of hex bar stock
from McMaster Karr
Hardened Multipurpose 4140 Alloy Steel Hex Bars Yield Strength: 105,000 psi
Hardness: Rockwell C35 (Hard)
These hex bars are hardened for increased abrasion and impact resistance. They are also stress relieved to reduce the chance of warping during machining. Also known as chrome-moly steel, this versatile 4140 alloy steel is used for a wide range of parts, such as gears, axles, shafts, collets, and die holders. It resists fracturing from repeated stress.
Wd. Wd. Tolerance Heat Treatment 1 ft. Lg. 3/4" -0.007" to 0.007" Hardened, Stress Relieved 6607K37 $22.52
Just cut a piece off to use until you find a real drive plug.