The HD74HC125, HD74HC126 require the 3-state control input C to be taken high to put the output into the high impedance condition, whereas the HD74HC125, HD74HC126 requires the control input to be low to put the output into high impedance.
Schematic symbols, PCB footprints, and 3D CAD models from SamacSys can be found by clicking on products in the Product Options table. If a symbol or model isn't available, it can be requested directly from the website.