I wouldn't consider poly - its great for locating but not for load. As with other accessory bushings, I'll use the OE rubber first.

Take any of these off of any 240 - serviced or not - and you'll see the uneven stress on the bushing - it sits on an edge, being pulled towards the side of less-little support. It flexes and stresses that bolt. Every one that breaks, does so in the same way and place. A large washer at the block would at least give it support on a complete surface to extremely limit or eliminate the lateral stress. I would have liked to see something that holds the bracket to the block, than just friction from a rubber bushing. You lose your PS, you drive it home with a workout. You lose your alternator, you're being towed. So yeah....sarcasm applies.