What size tool do you need to remove the engine mount bar bolts?

I think mine are 17mm, for the big center one, on a 73 mount.

The nut on the top side should be a 17mm, but may be a 15. The bolt wrench size is either 17mm or 8mm inhex (allen). The center bolts are 8mm inhex for the early bar, and a 13mm socket is used to remove the center nuts on the late bar. The Cap'n

The same size tool that you can use for anything on these cars...