I can't answer that directly, but from what I have seen, the arm on the 140 and 170 (and 240) are the same, just the reflector is different.
Hope this helps!
I also remember seeing some lower profile mounting brackets, you may want to look into those. they basically set the reflector of the 170 very close to the mounting plane, to gain a few mm.
I am going to scan a page from the most recent literature (I got the brochure from the offroad expo in October)
