You can use the X52 throttle with the 3D pro. The throttle will work alone without the stick since the USB cable is attached to it. When I had problems with my X52 stick I used the throttle with my ST290 stick. There are others here that have/are used/using the X52 throttle with a different stick.
Granted it won't provide multi-engine support but it will be more useful than the little throttle on the 3D pro.