Abstract: Gauge parts mounting blocks for the hooks and knives of a tufting machine have at least a pair of reference surfaces for acurate installation in the tufting machine while providing a mounting construction which allows individual gauge parts to be changed. Each block is an elongated member having gauge parts receiving slots spaced in the direction of elongation for receiving an attaching portion of a respective gauge part in side-by-side relationship. The slots open into a hollow which extends longitudinally through the member. Clamping inserts are received within the hollow and act against the attaching portion of the gauge parts. In the hook mounting block the upper surface of the hollow forms a reference surface against which the shanks are clamped.