Looking for T-handle casement cranks to replace old Hurd cranks

I have three 1986 era Hurd casement windows with traditional gold tone Hurd cranks for which I have ordered new window treatments (dual roller shades)

I would like to replace the existing crank handles with T-handles so the roller shades will not interfere.

The spline bore looks to be 3/8" inner diameter, the outer diameter for the handle looks to be 5/8" diameter, with two rows of 12 splines (as pictured).

I blindly purchased so-called "universal" fold-away handles elsewhere only to find out that they are not truly universal, but 11/32" (so a bit too small).

I researched online afterwards and found out this is not unusual for older era Hurd, Pella and Andersen casement windows.

I might add there is no number on the existing Hurd crank handle(s)... though looking at the Hurd website of obsolete parts, it appears their part number for this handle was likely 010768.

Is there a suitable T-handle which will work?

They are, in fact, a 3/8" spline.

As mentioned previously, I had purchased a set of "universal" fold-away cranks online (which didn't give specs).

When I received them, the small print on the packaging said fits the "most popular size" and the specs on the package said "standard 11/32" window operators."

Those were too small, and wouldn't fit... hence the post here.

Ah, the joys of having more obscure, and obsolete window hardware.

I'll see if the 39-298 T handle might work.

Thank you!