Tsuk 1/1 is much more difficult than the Kasamatsu used by Ellie Black, Oksana and … almost everyone.
Mary Lou did half-on, full-off. (1.5 twists total)
Kasamatsu is quarter-on, three quarter-off (1.0 twists total)
Watch it on YouTube. (Right hand on the horse first, left twist on the salto.)
In addition, she trained Tsuk double full. Seriously.
Click PLAY or watch it on YouTube.
https://www.youtube.com/watch?v=MffPhZ3rDgQ
Almost nobody does the more difficult version of Tsuk twisting. René Cournoyer from Canada is one.
If still confused on Kasamatsu, click over to Uncle Tim’s post – What the H is a Kasamatsu?
Gymnastics Coaching.com 
Was it possible to do a Kas on the women’s vaulting horse? I don’t think there was enough room to place your second hand on top of the horse. Mary Lou was amazing with that Tsuk full. She stuck it cold almost every time. I wonder what she could have done on today’s equipment.
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Yes women did compete Kasamatsu on the old crosswise horse.
The difference between that and Tsukahara is twist direction on the salto relative to first hand contacting the horse. If you put your right hand down first on round-off and twist to the right on the salto, that’s Kasamatsu. (easier)
If you put your left hand down first on round-off and twist to the right on the salto, that’s Tsuk 1/1. (more difficult)
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Retton actually competed the Tsuk double twist, at least in 1983, more than once I think her clubmate Diane Durham may have also trained it.
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