I've found a Stant 45967 and Gates 33747S that are close, and are shown on another vehicle application that uses the Motorad part (2004 Nissan 2.4L).

The only problem I see with them is they appear to have smaller primary disk openings and the bypass disk stem (on the bottom) is about 2.5mm shorter than the one called for. The Motorad is only about 1mm shorter. This means the bypass may not close completely when the thermostat is open. Probably wouldn't cause any trouble, but I'd prefer the Motorad piece.