Casement window crank Dyad 39-089?

A home owner from Brookline, MA says:
Hello, I was wondering if you could help identify this window crank. It appears to me to be a Dyad 5 inch from Truth hardware. The window hinge is on the right when viewing from the exterior of the building. Would this be part 39-089 or 39-090?
Also, part 39-187 is similar - would either work?
dyad crank
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Casey from SWISCO responded:

Hi, Remove the operator from the window and and carefully check to see which one matches up better. The zigzag of the crank arm differs between the two.

Back view displaying forearm length of the 39-090 sash crank operator.
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Tom from SWISCO responded:
It's tough to tell from this picture. The major difference between the 39-090 and 39-188 is the gear arm. It's a very subtle difference, but you can just make it out; the 39-090 gear arm has a "Z" shape while the 39-188 gear arm has more of a "W" shape. The gear arm in your picture is obscured by the window frame, however, so I can't quite make it out.
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