Big Block Alternator Fitting. Bushing or no Bushing?

That split bushing MUST have a little bit of clearance. It was designed to prevent stress from the assembly compressing the two alternator ears and "busting" then. The brackets tighten up on the front one, and slight irregularities in the whole assembly stack are taken up by the bushing being able to slightly slide.

I have no idea about the rest of the aftermarket pieces