Not sure about aftermarket, but they are not very complex and could easily be scratchbuild, as long as you have some wheels in the spares box.
Not much can be gathered from this pic. There's a wheel on each side with a hand pump/bar sticking aft, in the center. This UH-1 was in one of our hangers for a while, while they were shooting a remake of "Red Dawn". This one was in Vietnam, and still has all the patches from groundfire.
I got to work, just in time to see it departing into a "red dawn", on filming day.
