As I recall, the nut-end of the bolt faces the tranny. If you drill/cut the bolt-head off, how will you get the rest out?
I'd reccommend drilling two or three small holes inline on the nut (may need a cobalt drill-bit here), then splitting the nut with a chisel.
May need to remove the tranny-mount/bracket for more clearance here.

Happy Motoring, Mark

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DrDKW