Volvo tool 999-5761 is the 10mm sleeve that goes in the Counterhold 999-5760.
I have a counterhold (999-5760).
Anybody know of a 999-5761 alternative that is obtainable?


Yes that is what I am saying.
By the time one grinds a 10mm socket down to 13 mm length there is not enough meat to engage the extension and the bolt head without slipping. These are torqued to 80 Nm ( 60 ft-lbs ). The extension has got to be part of the tool, like a nut driver.
Might be able to modify the longer ones. Little concern about the shaft thickness. Might twist and snap at 80 Nm. Knuckle buster.