Upload & Sell: Off
It won't fit unless you remove some crap from the 1.4x TC. But the sigma 1.4x (and even the 2x) work well with it, so I wouldn't bother. The 1.4x especially, it's like they were designed with each other in mind. The 2x can be sharp but it loses some of it's af effectiveness and the image loses some of its luster.