Green’s Dictionary of Slang

block and tackle n.3

[rhy. sl. = SE shackle]

handcuffs.

[US]A.J. Pollock Und. Speaks 9/1: Block and tackle, a shackle (handcuffs or leg irons).
[UK]J. Franklyn Dict. of Rhy. Sl.
[UK]R. Puxley Fresh Rabbit.