FYI, that Backwoods kit DOES NOT fit the SW1500 as advertised. They made the kit to fit an earlier version of the SW frame, so you have to cut a LOT of material off the frame to hope to fit it.
Also, I had to play with the running boards so many times to try to get it to fit, I snapped off two wires to the trucks from the motor as Athearn never thought you'd have to put something over that part so closely so many times.
Then, after spending an entire weekend putting the kit together, turns out they also didn't know Athearn added the DCC boards, so the kit won't fit the locomotive at all. And I just spent the better part of a day cutting the frame up so there's no way I can return the SW now!
To say I'm disappointed is an amazing understatement. In fact, I'm about as angry as I ever thought possible for something like this. I have wasted an entire weekend, almost $100 for the mechanism and I think about 70-80 bucks for the kit, which will never fit the engine it was supposedly designed for.
My only hope is to maybe be able to grind away the interior of the hoods to fit the DCC and board. That material is very thick, maybe more than half an inch. That is the only hope I have of making a running model out of this. but for all the work you have to do a great deal of modifying to both the SW1500 and the kit, they really should warn you in advance. It's pretty much false advertising to say it snaps right on when nothing could be further from the truth...