We put a double step on our Casita and preferred it the single step, so I just did the same thing to our 19' Escape. (Credit to Larry at Little House Customs
and tractors1 on our forum for passing on Larry's advise.)
I ordered the Elkhart Tool and Die (ETD) 920 - may not be the best deal but I ordered from Amazon: Amazon.com: Elkhart (920 BOXED) 20" Double Step: Automotive
1) Remove the welded steel strap across the TOP of the step. (See post #42 by tractors1 in Entry Steps
.) I used a dremel to cut the end of the weld, and then a cold chisel to remove the strap.
2) Grind/sand it smooth and paint the bare metal.
3) Unbolt the old step - 4 bolts.
4) The old step mounts inside and under 2 pieces of angle iron with a reinforcing gusset on top. The new step mounts outside and on the same structure. The lip on the new step is narrow enough it fit perfectly along the gusset. (I thought I would have to remove part of the top lip on the step frame, but it fit without doing so.)
Slide the new step on the brackets and mark new holes on the top of the brackets using the 2 front holes on the step.
5) Remove the step and drill the 2 holes.
6) Put the step back on and bolt in the front 2 bolts with the nuts/washers on the outside/top of the bracket. (If you don't the bolt interferes with the step.)
7) Drill 2 holes through the bracket using the back SIDE (square) holes in the step frame.
8) Insert the remaining 2 bolts, nuts on the outside to make it easier to tighten them.
9) Lube the step pivot and slide bar.
10) Optional - I didn't do this yet. Angle cut the existing bracket to match the front of the step frame.
1 - original single step retracted
2 - original single step extended
3 - both steps in front of the door
4 - double step retracted
5 - double step half extended
6 - double step extended
7 - double step from the back
8 - double step from the front