You don't have radius rod sockets on the engine block. On the transmission casting maybe... ;)
So you have some sheared off studs. try a chisle or center punch to turn them. if nothing, use some lefty drill bits. you might find them semi- hard ( gr5 ), so you might start the hole with a small carbide regular drill bit, then switch tot he lefty and see if it will bite and snatch out. I almost always get a lefty to grab and unscrew them. if not, you can try a fluted or square profile extractor, once you have drilled out to just under thread diameter.