When will you have them in stock?
I would have to guess that they won't have them in stock for quite some time, as that's kinda' the deal with backorder. Nobody is really doing long-tubes on heavy duty trucks, so the options we have available don't really have much of a reason to produce them.
If you really want them, I would suggest placing your order with ARH and just going from there, unless GotExhaust or some other vendor could put a little more pressure on ARH to produce them.
I bought and installed my ARH long tubes about 2 years ago, and I remember it took me at least a few months to get them...but they're pretty nice and I feel well worth it. Between the headers and catback, along with the HemiFever tune, its really woken this truck up.
EDIT:
Also just saw this in the "Similar Threads" portion below this thread:
If anybody is waiting on a set of these,it looks like you're going to be waiting awhile.According to Matt Fikac ARH is moving,and the 2500 headers will be quite awhile before they start producing them again,apparently they're a low priority long tube,and will be one of the last ones they tool up...
www.ramforum.com
Sounds like their production in general is gonna be short for them for a while.