Hi,
Yeap I measured the same as you.. Was talking to nice TLR representative Tuesday night and he had no issues with fitting his gear diff. Then he mention he sanded down the "Top hat" side by about 0.5mm to give the diff a smoother action as it was felt the gears were just touching each other. By gently sanding this side down (800 grit) it allows the crown gear to sit closer to the internal gears.
So measured his geared diff and would you know it, it measured 17mm!!
Not had time to do it yet but feel this is the answer and root cause.
Thanks.
