stupid question about gearbox bolts

I'm changing my power box to a manual for clearance purposes. In removing the power box the two bolts closest to the engine came right out...... But the one by the fenderwell just spun. I got it loose and now my question is has anyone encountered this before? Is it supposed to be this way or did the welds break? What's the best way to put it back on? (I had to fenagle a pry bar in through a hole to hold it still)
Thanks fabo