Is this a crack

If it's an alloy housing it can be repaired and be about as safe as OEM, which isn't saying much. If it were mine, I would repair it and make some reinforcement pieces for it, both sides, and use it. As long as it wasn't for any super high powered project. I had a buddy in HS. owned a 68 RR that was pretty much totaled on account of housing failure one night. Took out the floor, all the way back to the rear axle being tweaked beyond use, leaf springs and mounts too. Personally not a big fan of any housing that isn't made from stamped steel and even then, prefer to have a mid support of some kind.