Maybe a dumb question but I can't find the answer...I've been reading that all HD narrow glide front ends were the same up until 2006. I have an 05 FXDL that I'm trying to convert to dual disc, but I'm having trouble locating the fork sliders without paying out the butt and ordering new from Harley.

Many of the dual disk forks/fork sliders for sale on ebay say 99 and earlier, but they are 39mm, so why wouldn't that fit my fork tubes? I've even found a set NIB that says for 2000 Dyna and 2002 XL Roadster only. What gives?

 

Because you have 41mm tubes(?)
http://www.motorcyclemetal.com/gpage25.html

 

There is a difference. 2000-2003 interchange. 2004-2005 39MM lower legs had larger front axle and will not interchange with earlier unless you use the matching axle/spacers/wheel bearings. 2000-down had different caliper mounts so you would have to use the inferior early style brakes. I do have a set of dual disc legs that came off an 05 Dyna but they are tubes and all.