I used a three foot extension for the unloader auger from fact machine shop in Palmer Ks, phone # is 785-944-3456. It is well made and does not vibrate just be carefull when you back up or turn with a 8 row corn head.
We have this one as well. The Stewart model just basically changes the discharge point from a bottom discharge(factory) to an end discharge(similar to Cat). While it does improve your throw it doesn't add much clearance due to the longing spout they use. The one from fact machine is either 30 or 36 inches and looks just like factory(after you paint it) and uses the original spout. You can have it one pretty easilly in an hour or so.
a bit slow to jump in here. Was wondering what header widths you guys were running. I need an extension that will give me the required reach for a 45' MacDon. Are the 36" extensions long enough for this header?