A system for attaching a PTO yoke to a tractor PTO output shaft comprises gripping a shaft of the PTO yoke using a clamp tool, whereby the clamp tool maintains a slide collar of the PTO yoke in a retracted position with respect to the yoke shaft, such that the yoke shaft is exposed for attachment to the tractor PTO output shaft. The clamp tool may comprise pliers, including plier jaws and plier handles; and a flexible band coupled to the plier jaws.