Mine didn't originally come with any extensions, but, I got the Camco versions to fit with a little persuasion (a little difficult to get on at first). Don't know what year you have or whether they changed the gutter style mid-year or not, but, a friend used the Camco version on his '11.
I'm beginning to think, though, if you bought your trailer used, that the previous owner may have altered your gutters...
You may just be stuck if you can't get the Camco version to fit...I used them on my new 5th wheel (Keystone), so, they appear to be fairly "universal". Oh, well, we tried.
My 2 cents, your mileage may vary...
2 Cats; J-Lo and Ragamuffin :R
2014 Thor Tuscany 40RX DP
2011 Ram 2500 Longhorn CTD HO
2011 Keystone Cougar 318SAB (now gone)
2008 FunFinder X 210WBS (Sadly gone)