Loaded question. But last I checked there were only 1-2 "bronco only" headers with 1 5/8" primaries. There are a few shorty options but they usually have to be modified to fit the bronco.
Hooker fenderwell P/N #9614 or 9814 cant quite remember right now and I believe the BC bronco headers have 1 5/8" primaries also.
I run the Hooker fenderwell headers and got them coated they are a little more pricey than most headers but they perform great and look great in the fenderwell. They do require a small 4"x6" maybe section cut out of each inner fender to fit through and they wont work with shock hoops one other draw back is its tough to run a exhuast cross over as they run outside the frame. But they do leave you with plenty of room around the engine.
Cant really speak about the BC headers but they appear to be very nice and I've heard of no fitment issues plus they allow shock hoops and a cross over. I may get a set for my 71 when I decide to modify it.