i have one from riviera, you have to drill your own bolt holes and for some reason mine is a bit wider than the bus, i still need to get some bolts to fit it on properly.
no more rusty bits is apparently all ready just to be bolted straight on.
being fiberglass means they should hopefully never rust, and they are a bit cheaper than trying to source nice staright bumpers.
only my rear is fiber as my bront bumper is straight.
they are lighter as well dont forget.