blueangel, the difference in the lower slider, I believe is the spacing/offset for caliper based on the wideglide hub. I did think about using the FLHTCU hub on the wheel assembly I bought, since it's a dual disc hub and all.... but I'm absolutely fine with a single disc up front... it's got plenty of stopping power actually... and I like the look of the WG hub.
As for fenders... not concerned too much about the mounting... I'll make whatever I like, work
afmm thanks for confirming that I shouldn't have too much issue with the 16x5.